DOHA / GENEVA / CAIRO - US Secretary of State Antony Blinken said on Wednesday that Hamas had proposed numerous changes, some unworkable, to a US-backed proposal for a ceasefire with Israel in Gaza, but that mediators were determined to close the gaps.

Senior Hamas official Osama Hamdan denied that the Palestinian Islamist group had put forward new ideas. Speaking to pan-Arab Al-Araby TV, he reiterated Hamas' stance that it was Israel that was rejecting proposals and accused the US administration of going along with its close ally.

Late on Wednesday, Hamas issued a statement stressing its "positivity" in the negotiations and urging the US to pressure Israel to accept an agreement leading to a permanent ceasefire in Gaza as well as full withdrawal from the enclave, reconstruction and release of Palestinian prisoner

White House National Security Adviser Jake Sullivan said many of Hamas' proposed changes were minor "and not unanticipated" while others differed more substantially from what was outlined in a UN Security Council resolution on Monday backing the plan put forward by US President Joe Biden.

READ MORE: UN: Immense scale of Gaza killings amount to crime against humanity

"Our aim is to bring this process to a conclusion. Our view is that the time for haggling is over," Sullivan told reporters.

Hamas also wants written guarantees from the US on the ceasefire plan, two Egyptian security sources told Reuters.

READ MORE: UN says Israel and Hamas committed war crimes; Gaza truce plan in balance

Late on Wednesday, Hamas issued a statement stressing its "positivity" in the negotiations and urging the US to pressure Israel to accept an agreement leading to a permanent ceasefire in Gaza as well as full withdrawal from the enclave, reconstruction and release of Palestinian prisoners.

The Palestinian group said that while US officials have said Israel has accepted a ceasefire proposal outlined by Biden on May 31, "we have not heard any Israeli official confirm this acceptance."

Biden's proposal envisages a truce and a phased release of Israeli hostages in Gaza in exchange for Palestinians jailed in Israel, ultimately leading to a permanent end to the war.

At a press conference with Qatar's prime minister in Doha, Blinken said some of the counter-proposals from Hamas, which has ruled Gaza since 2007, had sought to amend terms that it had accepted in previous talks.

Months of talks    

Negotiators from the US, Egypt and Qatar have tried for months to mediate a ceasefire in the conflict - which has killed tens of thousands of Palestinians and devastated the heavily populated enclave - and free the hostages, more than 100 of whom are believed to remain captive in Gaza.

READ MORE: Israel says Hamas rejected key elements of US ceasefire plan for Gaza

"Hamas could have answered with a single word: Yes," Blinken said. "Instead, Hamas waited nearly two weeks and then proposed more changes, a number of which go beyond positions that it had previously taken and accepted."

The US has said Israel has accepted its proposal, but Israel has not publicly stated this. Prime Minister Benjamin Netanyahu has repeatedly said Israel will not commit to ending its campaign before Hamas is eliminated

In its late Wednesday statement, Hamas said it had expressed its readiness to cooperate while Israel did not. Blinken's stance was "a continuation of the American policy complicit in the brutal genocide against our Palestinian people." The group said the US was providing political and military cover for Israel to press ahead with its assault on Gaza.

The US has said Israel has accepted its proposal, but Israel has not publicly stated this. Prime Minister Benjamin Netanyahu has repeatedly said Israel will not commit to ending its campaign before Hamas is eliminated.

Major powers are intensifying efforts to defuse the conflict in part to prevent it spiraling into a wider Middle East war, with a dangerous flashpoint being the escalating hostilities along the Lebanese-Israeli border.

The fighting in Gaza began on Oct 7 when militants led by Hamas burst across the border and killed 1,200 Israelis and took more than 250 hostage, according to Israeli tallies.

Israel's air and ground war since then has killed more than 37,000 Palestinians, according to Gaza's health ministry, displaced most of Gaza's population of 2.3 million and devastated housing and infrastructure.

The head of the World Health Organization said on Wednesday many people in Gaza were facing "catastrophic hunger and famine-like conditions", with over 8,000 children under five years old diagnosed and treated for acute malnutrition.

READ MORE: Hamas accepts UN-backed Gaza truce plan, US cites 'hopeful sign'

A UN inquiry found that both Israel and Hamas had committed war crimes early in the Gaza war, and that Israel's actions also constituted crimes against humanity because of the immense civilian losses.

Israel continues assaults in Gaza

As diplomats sought a ceasefire deal, Israel continued assaults in central and southern Gaza that are among the bloodiest of the war.

Israeli forces stepped up air and tank bombardment on Wednesday night in Rafah and central Gaza, residents said. An Israeli air strike on a house in Al-Nuseirat refugee camp killed three people, medics said.

Residents earlier said Israeli forces pounded areas across Gaza on Wednesday as tanks advanced towards northern Rafah, which skirts the Egyptian border.