A new round of Gaza ceasefire talks was underway in the Qatari capital Doha on Thursday afternoon, an official briefed on the meeting told Reuters, with Israel's spy chief joining his U.S. and Egyptian counterparts and Qatar's prime minister for the closed-door meeting.

The talks, an effort to end 10 months of fighting in the Palestinian enclave and bring 115 Israeli and foreign hostages home, were put together as Iran appeared on the point of retaliating against Israel following the assassination of Hamas leader Ismail Haniyeh in Tehran on July 31.

With U.S. warships, submarines and warplanes dispatched to the region to defend Israel and deter potential attackers, Washington is hoping a ceasefire agreement in Gaza can defuse the risk of a full-out wider regional war.

Hamas officials, who have accused Israel of stalling, did not join Thursday's talks. However mediators planned to consult with Hamas' Doha-based negotiating team after the meeting, the official briefed on the talks told Reuters.

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

CIA Director Bill Burns and U.S. Middle East envoy Brett McGurk represented Washington at the talks, convened by Qatari prime minister Sheikh Mohammed bin Abdulrahman Al Thani, with Egypt's intelligence chief Abbas Kamel also in Doha.

Israel and Hamas have each blamed the other for failure to reach a deal but in the run-up to Thursday's meeting, neither side appeared to rule out an agreement.

A source in the Israeli negotiating team said on Wednesday that Prime Minister Benjamin Netanyahu has allowed significant leeway on a few of the substantial disputes.

Gaps include the presence of Israeli troops in Gaza, the sequencing of a hostage release and restrictions on access to northern Gaza.

In the lead-up to Thursday's talks, Hamas, which rejects any U.S. or Israeli intervention in shaping the "day after" the war in Gaza, told mediators that if Israel made a "serious" proposal that is in line with Hamas' previous proposals the group would continue to engage in negotiations.

Senior Hamas official Sami Abu Zuhri told Reuters on Thursday that the group is committed to the negotiation process and urged mediators to secure Israel's commitment to a proposal Hamas agreed to in early July, which he said would end the war and required a full withdrawal of Israeli troops from Gaza.

Even as negotiators arrived in Qatar, fighting continued in Gaza, with Israeli troops hitting targets in the southern cities of Rafah and Khan Younis.

After months of a war which has laid waste to Gaza, killed more than 40,000 Palestinians, according to Gaza health officials, and driven almost all of its 2.3 million population from their homes, there was a desperate desire for an end to the fighting.