The US increased pressure on Hamas on Tuesday to disarm in the next phase of an already fragile Gaza ceasefire as President Donald Trump pushed to cement an end to the devastating conflict.

In a visit to Israel, US Vice President JD Vance said the ceasefire plan was going better than expected but warned the Palestinian militant group it would be obliterated if it did not cooperate, echoing a Trump threat earlier in the day of "fast, furious and brutal force".

Israel and Hamas have accused each other of repeated breaches of the truce since it came into effect 11 days ago, with flashes of violence and recriminations over the pace of returning hostage bodies, bringing in aid and opening borders.

Israel has killed at least 87 Palestinians since the ceasefire began, according to the Gaza health ministry, and two Israeli soldiers were killed in southern Gaza over the weekend.

A delegation from Hamas said at a meeting with Turkish government officials on Tuesday that the group remains committed to the ceasefire deal despite what it called Israel's "repeated violations," according to a Hamas statement.

Turkey was among the signatories of Trump's document on the Gaza ceasefire deal earlier this month in Egypt's Sharm el-Sheikh.

With the existing truce already shaky, the US and mediators Egypt, Qatar and Turkey are trying to push towards the far more complicated second phase of talks that asks each side to make concessions that have previously torpedoed peacemaking.

Trump's 20-point ceasefire plan demands the disarmament of Hamas, to which the group has so far refused to agree, a concurrent Israeli withdrawal from Gaza and a path towards a Palestinian state.

Vance, who will meet Israeli Prime Minister Benjamin Netanyahu on Wednesday, said he was optimistic about the truce, and held out the prospect of more Gulf states eventually seeking to normalise ties with Israel.

But he moved to modify expectations for a rapid return of the bodies of all hostages, a key Israeli demand, and said a full realisation of the ceasefire plan would take a lot of work and "a very, very long time".

Major unresolved issues include governance and security control in Gaza, with Trump's plan calling for the formation of a technocratic body under an international oversight board that Trump would oversee, and the creation of a multinational force, with no role for Hamas.

Vance, who was visiting a military facility in southern Israel where US troops are monitoring the truce, said the US, Israel and Gulf states were all agreed that though Hamas fighters could receive clemency, the group would have to disarm.

"If Hamas doesn't cooperate, as the president of the United States has said, Hamas is going to be obliterated," Vance warned. (Reuters)