U.S. officials had seen Mr. Sinwar as a major obstacle to negotiations, and hoped that since his killing the armed group’s surviving leaders might be more open to making a deal with Israel to end the yearlong war in Gaza and release the dozens of hostages remaining there. Mr. Blinken traveled to the Middle East this week at President Biden’s request in the hope of jump-starting talks that have been frozen for months.

But during their joint news conference, neither Mr. Blinken nor Mr. Al Thani offered any sign that Hamas’s position had softened.

Mr. Al Thani said that Qatar had “re-engaged” with Hamas in the week since Mr. Sinwar’s death, via political representatives of the group who maintain an office in Doha, and sensed that Hamas maintains “the same position” as it has since the last formal negotiating proposal it offered months ago. Israel and the United States have rejected that position as unacceptable.

Mr. Al Thani added that Egypt was also playing a role in trying to revive the cease-fire talks, saying that “there are ongoing discussions between Egypt and Hamas.” He did not detail the nature of those discussions.

Mr. Blinken also did not provide details about when the new talks might start, or if the United States might propose any new positions.

For months, the Biden administration has pursued a three-phase agreement that would begin with a six-week pause in fighting during which the remaining hostages would be released from Gaza in exchange for Palestinians being held in Israeli prisons. The second phase envisions a permanent cease-fire, and the third provides for a multiyear reconstruction plan for Gaza.

U.S. officials said this week that the Biden administration was open to considering fresh proposals, potentially including a shorter pause in Israel’s offensive in exchange for the release of just some of the hostages.

Mr. Blinken, who previously visited Israel and Saudi Arabia this week, emphasized that ending the war in Gaza requires that “we continue to develop a plan for what follows, so that Israel can withdraw, so that Hamas cannot be constituted and so that the Palestinian people can rebuild their lives, rebuild their futures under Palestinian leadership.”

Mr. Blinken and Mr. Al Thani, who met for more than an hour before addressing reporters, said they had also spoken at length about how to end Israel’s offensive in Lebanon against the Iranian-backed Hezbollah militia in a way that would ensure Israel’s security.

“There has been a lot of talk in recent days of a war of civilizations, or of civilizations that must be defended. I’m not sure you can defend a civilization by sowing barbarism yourself,” he said at the opening of the conference in Paris held to help raise funds for Lebanon.

Mr. Macron did not specify exactly how France would support the recruitment of additional troops for Lebanon, whose bitter sectarian divisions and weak central government have helped Hezbollah, a Shiite movement backed by Iran, to gain power.

Thursday’s meeting is the latest example of Mr. Macron’s bid to wield influence in Lebanon, a former French mandate. The historical ties, as well as the fact that French is spoken alongside English and Arabic, the official language, have long given Paris a sense of responsibility toward the country. France, for example, is one of the largest contributors of troops to the U.N. peacekeeping mission in Lebanon.

At the same time, the United States, Israel’s leading backer, remains the region’s most powerful diplomatic force. President Biden’s envoy on the Israel-Hezbollah conflict, Amos Hochstein, visited Beirut this week, and met with Lebanese officials. The State Department said it would send its deputy secretary for management, Richard Verma, to the Paris conference.

Lebanon’s caretaker prime minister, Najib Mikati, also called for a cease-fire at the conference and said that Israeli attacks had put 13 Lebanese hospitals out of service. More than 1.2 million people have fled their homes because of the conflict, the United Nations said more than two weeks ago.

Mr. Mikati said that his government could deploy additional troops to the south as part of any cease-fire deal. The military, which receives support from the United States, is not a party to the conflict and Israel has said repeatedly that it is at war with Hezbollah, not Lebanon. Still, Lebanon refers to Israel as the enemy and does not have diplomatic ties with the country.

Lebanon’s government is largely powerless to rein in Hezbollah or deploy additional troops to the southern border without Hezbollah’s consent. Lebanese officials, including, Mr. Mikati, say that Hezbollah is on board with a nearly 20-year-old U.N. resolution that would allow them to do so, but Hezbollah has not yet publicly said this.

The C.I.A.’s website said Lebanon’s military had around 73,000 active troops, but experts say it has been severely weakened by the country’s economic crisis. Israeli forces killed three Lebanese soldiers this week in southern Lebanon. Israel apologized. On Thursday, Lebanon’s military said that another Israeli attack had killed three more of its soldiers in the south.

Mr. Macron appealed to the conference to support a plan to recruit at least 6,000 additional soldiers and enable the deployment of at least 8,000 additional soldiers in the south.

This is not the first donor conference that Mr. Macron has organized for Lebanon. After a port blast devastated parts of Beirut in 2020, he toured the city before Lebanese politicians did, and held a conference that raised hundreds of millions of dollars.

Euan Ward and Ségolène Le Stradic contributed reporting

The arrests came a day after both the U.S. Embassy in Sri Lanka and Israel’s National Security Council warned their citizens to avoid Arugam Bay, a popular surf destination.

The U.S. Embassy said it had “received credible information warning of an attack targeting popular tourist locations in the Arugam Bay area. Due to the serious risk posed by this threat, the Embassy imposed a travel restriction on Embassy personnel for Arugam Bay effective immediately and until further notice.”

Israel’s National Security Council told its citizens to “immediately leave Arugam Bay and the south and west coastal areas of Sri Lanka.” Israel also warned people to avoid public displays of anything that could be identified as Israeli, including clothing with Hebrew writing or religious symbols, and to avoid gathering in groups.

Britain also updated its travel advisory for Sri Lanka, citing a heightened terrorist threat. “Attacks could be indiscriminate, including in places visited by foreign nationals such as hotels, tourist sites and places of worship,” the travel advice stated.

The police in Sri Lanka had already increased security measures in Colombo, the capital, as well as in Ella and Weligama, popular destinations for Israeli tourists, a police spokesman said during an earlier news conference. One of the reasons for the heightened security, he added, was that some tourists had set up temporary prayer halls because of a Jewish holiday.

Pamodi Waravita contributed reporting from Sri Lanka.

Israel’s military said it was looking into whether its forces had “accidentally harmed” Lebanese soldiers while conducting raids in the area against Hezbollah, the Lebanese militant group. It said in a statement that it “does not intentionally target soldiers of the Lebanese army,” and added: “The incident is under review, and any lessons will be learned.”

Lebanon’s military is not a party to the conflict between Israel and Hezbollah, the powerful Iranian-backed armed group whose military assets dwarf those of the country’s government.

But Lebanese troops have increasingly been caught in the crossfire: Thursday was at least the fourth time this month that Israeli troops had killed Lebanese soldiers amid their fight against Hezbollah. This week, the Israeli military apologized over the deaths of three other Lebanese soldiers, saying that it was “not operating against the Lebanese army.”

As Israeli troops engage in a weekslong ground invasion of southern Lebanon, the Israeli military has kept up aerial bombardment across the country, in particular in the Dahiya, a densely populated urban area near Beirut where Hezbollah holds sway.

The Israeli military said Thursday that overnight strikes in the area had targeted “civilian buildings in the heart of populated areas” that Hezbollah had used to manufacture or store weapons, adding that it had issued evacuation orders for residents of the buildings.

The Lebanese television channel al-Mayadeen, which is broadly viewed as pro-Iran and pro-Hezbollah, said that one of its offices was hit. Video broadcast by the channel showed the concrete shell of a building surrounded by shattered glass and twisted metal.

Al-Mayadeen said the Israeli military had not issued a warning before striking its offices, which the channel’s employees had vacated at the start of Israel’s invasion. There were no reports of injuries. It said in a statement that it “holds the Israeli occupation responsible for targeting a well-known media office belonging to a prominent news channel.”

Palestinian Civil Defense, the emergency service, has been responding to the scenes of attacks to treat the wounded and try to pull people from rubble. But on Wednesday night, it said its work in northern Gaza had “completely ceased.”

“The situation has become catastrophic,” it said in a statement on Telegram. “The residents there are left without humanitarian services.”

The statement said three of its rescue workers had been injured by an Israeli drone strike and that five others had been detained by Israeli forces. It added that Israeli tanks had shelled the only fire truck operating in northern Gaza.

The Israeli military did not immediately respond to a request for comment.

United Nations officials have expressed alarm about the humanitarian situation in northern Gaza, and said the Israeli authorities have denied aid workers’ requests to help find survivors in the aftermath of Israeli strikes.

Gloria Lazic, an aid worker with the U.N. Office for the Coordination of Humanitarian Affairs, said on social media this week that requests by the agency to help people trapped under rubble in the northern town of Jabaliya had been “repeatedly denied by the Israeli authorities.”

Philippe Lazzarini, the head of the main U.N. agency for Palestinians, said much the same in a social media post the same day, writing that “in northern Gaza, people are just waiting to die.”

Rawan Sheikh Ahmad contributed reporting.

Al Jazeera strongly denied the accusations, which it said were based on “fabricated evidence” and followed a long history of Israeli hostility toward the network. The authenticity and accuracy of the documents could not be immediately confirmed.

The accusations against the six journalists were only the latest chapter in Israel’s campaign against Al Jazeera. The organization’s Arabic-language service is widely seen in Israel as being close to Hamas, and critics have accused the network of amplifying the armed group’s perspective.

The channel’s correspondents are also some of the few remaining reporters on the ground in Gaza to document the devastating impact of Israel’s operations there. Israel has largely barred the international press from entering the enclave except on closely monitored tours accompanied by the Israeli military.

In its statement, Al Jazeera called the accusations “a blatant attempt to silence the few remaining journalists in the region, thereby obscuring the harsh realities of the war from audiences worldwide.”

Since the beginning of the war in Gaza, Israel has taken steps to crack down on Al Jazeera, including passing a new security law that it used to shutter many of the network’s operations in the country.

Press freedom advocates have criticized Israel’s measures against the news organization, calling them a serious threat to journalistic independence. They also argue that the law used to curb its activities sets a concerning precedent that could be used to prevent other international media organizations from operating in Israel.

The Committee to Protect Journalists, a press freedom monitor, said in a statement following the latest accusations that Israel had “repeatedly made similar unproven claims without producing credible evidence.”

The journalists named by Israel on Wednesday included Anas al-Sharif and Hossam Shabat, two of the last reporters in northern Gaza, where Israeli forces have launched a renewed military operation in recent days to oust what they call a Hamas insurgency. At least one of the journalists, Mr. Shabat, wrote posts on social media praising Hamas, and uploaded photos of himself wearing the green-and-white scarf of its student movement.

On Wednesday, Mr. Shabat said in a social media post that the Israeli accusations were intended to turn him and his colleagues into “killable targets.”

In late July, Israel killed Ismail al-Ghoul, an Al Jazeera reporter in Gaza, in an airstrike, claiming that he was a member of Hamas’s military wing. Al Jazeera rejected the allegation as “baseless.” A cameraman, Rami al-Rifee, was also killed in the strike; the Israeli military did not accuse him of being a militant.

Two months later, Israeli soldiers raided the channel’s offices in the Israeli-occupied West Bank and ordered them closed for at least 45 days.