Hamas has announced it will take part in a new round of ceasefire talks in Cairo, as the body of an Israeli hostage has been found in the southern Gaza city of Khan Younis, the Israeli military said. Six months into the war, repeated attempts at brokering a second truce, after a week-long pause at the end of November in which hostages and Palestinian prisoners were exchanged, have failed. But Hamas, Gaza’s Islamist rulers, said on Saturday that they would send a delegation to the Egyptian capital for a new round of mediated talks beginning on Sunday. Hamas reiterated its demands issued in a 14 March proposal before a UN security council resolution calling for a ceasefire in the Gaza Strip that was passed on 25 March. The demands include a permanent ceasefire, the withdrawal of Israeli forces from Gaza, a return of the displaced, and a “serious” exchange deal of Palestinian prisoners for Israeli hostages being held in Gaza, the statement said. Israel has repeatedly vowed that it will fight on in the Palestinian territory until Hamas is destroyed. The CIA director Bill Burns is expected to attend Sunday’s talks, along with the Qatari foreign minister, Sheikh Mohammed bin Abdulrahman Al Thani, and an Israeli delegation, Egypt’s Al Qahera news reported. Israel was undecided on whether to attend, an Israeli official said, citing concern that the event would be “more political theatre than actual progress”. Meanwhile, the body ofElad Katzir, a 47-year-old farmer from Nir Oz kibbutz, was unearthed by commandos in southern Khan Younis overnight, the Israel Defense Forces (IDF) said. He had been killed by his Palestinian Islamic Jihad (PIJ) captors and buried there in mid-January, it said, citing intelligence information without giving further details. There was no immediate comment from PIJ. In an 8 January video posted by PIJ online, Katzir said: “I was close to dying more than once. It’s a miracle I’m still alive … I want to tell my family that I love them very much and I miss them very much.” News of Katzir’s death comes as a new wave of protests calls for Israel’s prime minister, Benjamin Netanyahu, to do more to secure a new hostage deal, and to call early elections. Katzir’s sister, Carmit Palty Katzir, blamed the Israeli authorities for her brother’s death, saying he would have returned alive had the authorities agreed to a new truce deal. “Our leadership is cowardly and driven by political consideration, which is why this deal has not happened yet,” she wrote on her Facebook page. “Prime minister, war cabinet, and coalition members: look at yourself in the mirror and say if your hands didn’t spill blood.” Campaign group the Hostages and Missing Families Forum said Katzir had been alive for three months after his abduction, during which time “signs of life and reports about his condition reached Israel”. “Three months in which there was a possibility to save him and return him alive to his family and his country … The return of Elad Katzir’s body is a painful, immediate, and harsh reminder that time has long run out for the hostages.” Katzir’s father, Avraham, was killed on 7 October, during the Hamas attack in which militants killed 1,200 people and seized another 250 as hostages. His mother, Hanna, was freed in the November truce. Officials have said that they believe at least 35 of the remaining 130 hostages have died in captivity. Israel is also facing mounting international pressure to justify its conduct in the war in Gaza, where the local health ministry says 33,000 people have been killed and aid agencies say famine is taking hold because of Israeli obstruction of aid. IDF ground troops have been bogged down in Khan Younis for weeks, and Netanyahu has repeatedly threatened an invasion of the Gaza Strip’s southernmost town, Rafah, where about 85% of the population of 2.3 million have sought shelter. Joe Biden, who has provided strong diplomatic and military backing for Israel’s offensive, has voiced anger at an Israeli drone attack that killed seven aid workers earlier this week. In a phone call on Thursday, he pressed Netanyahu to take concrete action to protect humanitarians and civilians. While US rhetoric on the humanitarian crisis in Gaza has strengthened of late, critics say Biden has opted not to use Washington’s leverage as Israel’s principal arms supplier and most important international ally to bring it to the negotiating table, or get it to increase the flow of aid to the territory’s desperate population. Guardian Newsroom: Crisis in the Middle East On Tuesday 30 April, 7-8.15pm GMT, join Devika Bhat, Peter Beaumont, Emma Graham-Harrison and Ghaith Abdul-Ahad as they discuss the fast-developing crisis in the Middle East. Book tickets here or at theguardian.live