The United States hailed a "promising start" to Gaza ceasefire talks Thursday, as pressure mounted for a deal to halt the spread of a war in which Israel has killed over 40,000 Palestinians.
Israel's onslaught has devastated Gaza, displaced nearly all of its population at least once and triggered a towering humanitarian crisis.
Talks involving CIA director William Burns opened in the Qatari capital Doha, US National Security Council spokesman John Kirby said.
It was not immediately clear if Hamas had sent any delegates to the meeting, which Israel planned to attend.
"Today is a promising start," Kirby told reporters in Washington, adding: "There remains a lot of work to do."
The talks were expected to continue on Friday, he said.
"We need to see the hostages released, relief for Palestinian civilians in Gaza, security for Israel and lower tensions in the region, and we need to see those things as soon as possible," he added.
So far, there has been only one, week-long truce in November, when Gaza militants released 105 hostages seized in the October 7 attack, the Israelis among them in exchange for 240 Palestinian prisoners held in Israeli jails.
A Hamas official said the Islamist movement would demand the implementation of the plan that Biden said would start with an initial six-week "complete ceasefire", the release of hostages and a "surge" in humanitarian aid as the warring sides negotiate "a permanent end to hostilities".
The latest diplomatic push comes as the Gaza health ministry said the death toll in the besieged Palestinian territory had surpassed 40,000 -- which UN human rights chief Volker Turk called a "grim milestone".
"Most of the dead are women and children. This unimaginable situation is overwhelmingly due to recurring failures by the Israeli Defense Forces to comply with the rules of war," he added.
The Gaza health ministry said the tally included 40 deaths in the previous 24 hours.
In the most deadly bombing, rescuers said air strikes killed five people in Gaza City.
Israel's military said troops had killed about 20 militants in Rafah, southern Gaza.
On Wednesday, dead and wounded including bloodied children arrived at Nasser Hospital in the southern city of Khan Yunis after an Israeli strike.
"I was not pro-Hamas but now I support them and I want to fight," one grieving man shouted.