The United States, Egypt and Qatar have released a joint statement calling on Israel and Hamas to resume negotiations over a ceasefire and hostage-release deal.

The statement said the three nations had forged a “framework agreement” that had “only the details of implementation left to conclude”.

Israel said it would send negotiators to the proposed talks, which are pencilled in for 15 August in Doha or Cairo. Hamas did not immediately respond.

The renewed diplomatic push will be seen as an attempt to stop regional tensions from spiralling out of control, after Hamas’ leader Ismail Haniyeh was assassinated last week. Iran, blaming Israel, has vowed a response – though Israel has not commented directly on the killing.

In a joint statement, the three nations invited Israel and Hamas to restart talks on 15 August “to close all remaining gaps and commence implementation of the deal without further delay.”

“As mediators, if necessary, we are prepared to present a final bridging proposal that resolves the remaining implementation issues in a manner that meets the expectations of all parties,” it said.

The statement was signed by US President Joe Biden, Egyptian President Abdel Fattah el-Sisi, and the Emir of Qatar Sheikh Tamim bin Hamad Al Thani.

It said the framework agreement was based on “principles” previously outlined by President Biden on 31 May – which would start with a full ceasefire and the release of a number of hostages – and endorsed by the UN Security Council.

US Defence Secretary Lloyd Austin said in a statement on Thursday evening he had spoken with Israeli Defence Minister Yoav Gallant to brief him on changes to US forces in the region and “reinforce my ironclad support for Israel’s defense”.

“I also stressed the importance of concluding a ceasefire deal in Gaza that releases the hostages,” he said.

Despite numerous rounds of talks, the challenge of reaching a ceasefire and hostage release agreement has so far proved elusive.

Hamas is pushing for a ceasefire, but Israeli Prime Minister Benjamin Netanyahu has said the conflict can only stop once Hamas is defeated.

On Thursday, Israel continued its bombardment of the Gaza strip. Gaza’s Hamas-run civil defence force said it hit two schools, killing more than 18 people. The Israeli military said it had struck Hamas command centres.

Any proposed talks could be made even more difficult by Hamas’ decision to elect Yahya Sinwar as its new leader, replacing Haniyeh.

Sinwar, who Israel holds responsible for the planning and execution of the 7 October attacks, is seen as one of the group’s most extreme figures.

Amid fears of an attack from Iran or its allies, Israel’s security cabinet met in an underground bunker on Thursday, instead of its usual meeting place, Israel’s Channel 13 reported.