The international food charity World Central Kitchen has called for an independent investigation into the Israeli strikes that killed seven of its aid workers in Gaza on Monday, as Joe Biden and Benjamin Netanyahu held their first phone call since the attack. WCK asked Australia, Canada, Poland, the US and the UK, whose citizens were killed, to join it in demanding “an independent, third-party’’ inquiry into the strikes. “This was a military attack that involved multiple strikes and targeted three WCK vehicles,” the charity said in a statement. “All three vehicles were carrying civilians; they were marked as WCK vehicles; and their movements were in full compliance with Israeli authorities, who were aware of their itinerary, route and humanitarian mission. “An independent investigation is the only way to determine the truth of what happened, ensure transparency and accountability for those responsible, and prevent future attacks on humanitarian aid workers.” WCK asked the Israeli government to retain all the necessary evidence, including communications, video and audio recordings of the fatal strikes on their convoy. The bodies of six foreign staff of WCK were repatriated from Gaza via Egypt on Wednesday, while the Palestinian employee was buried in Gaza. The Australian prime minister, Anthony Albanese, said on Thursday that Israel’s explanation for the deaths was “not good enough”, while a diplomatic crisis between Poland and Israel has erupted after Israel’s ambassador to Poland, Yacov Livne, pushed back at what he said were attempts by the “extreme right and left in Poland” to accuse Israel of “intentional murder”. The Polish president, Andrzej Duda, on Thursday called the comment “outrageous” and described the ambassador as “the biggest problem for the state of Israel in relations with Poland”. The foreign ministry said Livne was summoned to a meeting on Friday morning. Biden and Netanyahu spoke on Thursday for less than 30 minutes, the White House official said, in their first phone call since the strikes. A US official said before the phone call that Biden was likely to bring up the need for better protections for humanitarian workers and for an increase of food shipments into Gaza, Reuters reported. The US president has led a chorus of international anger over the attack on the employees of the US-based WCK, who were distributing desperately needed food to a population on the verge of famine. The Pentagon said the US secretary of defense, Lloyd Austin, had urged Israel to take concrete steps to protect aid workers and Palestinian civilians in Gaza “after repeated coordination failures” when he spoke with his Israeli counterpart, Yoav Gallant, on Wednesday. “Secretary Austin expressed his outrage at the Israeli strike on a World Central Kitchen humanitarian aid convoy,” the Pentagon said. It added that Austin had urged Gallant to conduct “a swift and transparent” investigation, to share the conclusions publicly, and to hold those responsible to account. The US has provided crucial military aid and diplomatic support for Israel’s nearly six-month offensive, which was launched in response to Hamas’s 7 October attack in southern Israel. There is no indication the US will withdraw aid over the WCK strike. Israel said on Thursday that the military investigation into the killing of the seven aid workers could take weeks, while Shimon Friedman, a spokesperson for Cogat, the arm of the Israeli military responsible for civilian affairs in the Palestinian territories, told the BBC they “hope for [the investigation to report] in the next few days”. The IDF chief of staff, Herzi Halevi, attributed the strike to “misidentification”, adding that it “was not carried out with the intention of harming WCK aid workers”, and was a mistake that should not have happened. During a media briefing on Thursday, the Israeli government spokesperson Raquela Karamson said “clearly something went wrong’’ and that the army ‘‘would adjust’’ its Gaza war tactics after the killings. “We will certainly adjust our practices in the future to make sure this does not happen again,” she said. The IDF said it had halted leave for all combat units on Thursday and heightened its air defence command to deal with a possible missile or drone attack from Iran. There is concern in Israel about Tehran’s response to the deaths of two Iranian generals and five military advisers in an Israeli airstrike on an Iranian diplomatic compound in Damascus earlier this week. Reuters and Tel Aviv residents reported on Thursday that GPS services had been disrupted, an apparent measure to ward off guided missiles. Iran has vowed revenge for the killings. Since the war began, Netanyahu has faced intense domestic pressure from the families and supporters of the hostages still being held in Gaza, and from a resurgent anti-government protest movement. On Wednesday Benny Gantz, a Netanyahu rival and member of the war cabinet, called for snap parliamentary elections in September. “We must set a consensual date for the month of September, or if you prefer for the first anniversary of the war,” Gantz said. The prime minister’s Likud party rejected the call, but it was welcomed by the leader of the US Senate, Chuck Schumer, who last month urged new elections in a strident criticism of Netanyahu’s handling of the conflict. “When a leading member of Israel’s war cabinet calls for early elections and over 70% of the Israeli population agrees according to a major poll, you know it’s the right thing to do,” Schumer wrote on X. Early elections require the agreement of 61 elected officials, or the majority of deputies in the Knesset, where the Likud has the most seats but does not have a majority. Likud said a national election while Israel was at war “would inevitably lead to paralysis” and harm the military’s fight in Gaza. Meanwhile, at a press conference held in Beirut on Thursday, a Hamas official, Osama Hamdan, said there had been no progress in Gaza ceasefire talks despite the Palestinian group showing flexibility. “The occupation government is still evading, and negotiations are stuck in a vicious circle,” Hamdan said, adding that Netanyahu was placing obstacles that were hindering both parties from reaching an agreement. More than 33,000 Palestinians have been killed in the war, Gazan medical officials say. Hamas has said 6,000 of its fighters are among the fatalities. Israeli officials say the Palestinian combatant death toll is more than twice that number. 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