Hamas said on Wednesday it would not take part in a new round of Gaza ceasefire talks slated for Thursday in Qatar, but an official briefed on the talks said mediators expected to consult with the Palestinian group afterwards.

The U.S. has said it expects indirect talks to go ahead as planned in Qatar's capital Doha on Thursday, and that a ceasefire agreement was still possible, while warning that progress was needed urgently to avert a wider war.

However Axios reported that U.S. Secretary of State Antony Blinken has postponed a trip to the Middle East that had been expected to begin on Tuesday.

Three senior Iranian officials have said that only a ceasefire deal in Gaza would hold Iran back from direct retaliation against Israel for the assassination of Hamas leader Ismail Haniyeh on its soil last month.

"Israel will send the negotiations team on the agreed upon date, that's tomorrow August 15th, in order to finalise the details of the implementation of the framework agreement," government spokesperson David Mencer said in a briefing.

The delegation includes Israel's spy chief David Barnea, head of the domestic security service Ronen Bar and the military's hostages chief Nitzan Alon, a defence official said.

Hamas has voiced scepticism about the chances of the talks delivering real results, blaming Israel for stalling, while Israeli Prime Minister Benjamin Netanyahu says that Hamas leader Yahya Sinwar has been the main obstacle to sealing a deal.

"Going to new negotiations allows the occupation to impose new conditions and employ the maze of negotiation to conduct more massacres," Senior Hamas official Sami Abu Zuhri told Reuters.

Hamas' absence from the talks, however, does not eliminate the chances of progress since its chief negotiator Khalil al-Hayya is based in Doha and the group has open channels with Egypt and Qatar.

"Hamas is committed to the proposal presented to it on July 2, which is based on the U.N. Security Council resolution and the Biden speech and the movement is prepared to immediately begin discussion over a mechanism to implement it," said Abu Zuhri.

A source familiar with the matter said that Hamas wants the mediators to come back to them with a "serious response" from Israel. If that happens, the group says, it will meet with mediators after the Thursday session. An official briefed on the talks process said mediators expected to consult with Hamas.