The US says it has "credible reports" that Hamas is planning an "imminent" attack on civilians in Gaza, which it says would be a "direct and grave" violation of the ceasefire agreement.

A planned attack against Palestinians would "undermine the significant progress achieved through mediation efforts", the State Department said.

The statement did not provide further details on how this would be a breach of the US-brokered ceasefire agreed with Israel.

Hamas has strongly denied any planned imminent attack and has, in turn, accused Israel of supporting rival armed groups in Gaza. It has, however, been re-establishing control in the power vacuum that followed the Israeli partial withdrawal.

The state department said it had already informed other guarantors of the Gaza peace agreement, which includes Egypt, Qatar and Turkey, and demanded Hamas uphold its end of the ceasefire terms.

"Should Hamas proceed with this attack, measures will be taken to protect the people of Gaza and preserve the integrity of the ceasefire," the US statement said.

President Donald Trump has previously warned Hamas against the killing of civilians.

"If Hamas continues to kill people in Gaza, which was not the Deal, we will have no choice but to go in and kill them," Trump said in a post on Truth Social earlier this week.

He later clarified that he would not be sending US troops into Gaza.

Last week, BBC Verify authenticated graphic videos that showed a public execution carried out by Hamas gunmen in Gaza.

Fierce clashes erupted a week ago - involving Hamas security forces and armed members of the Dughmush family in Gaza City.

Twenty-seven people were killed in what was one of the most violent internal confrontations since the end of major Israeli operations in the enclave.

The Israel Defence Forces (IDF) still occupy and control just over 50% of the Gaza Strip, having withdrawn, under Phase 1 of the Trump plan, to an agreed 'Yellow Line'.

There are concerning reports that Gaza gangs, which have looted aid convoys, are currently able to move with impunity in the eastern part of the territory under Israeli control.

Hamas, which has ruled the territory for 18 years, is facing a challenge from armed groups, such as Abu Shabab's Popular Forces, gangs which it says are being armed and supported by Israel.

It has recalled about 7,000 members of its security forces to reassert control in Gaza, according to local sources.

Under the Trump 20-point ceasefire, Hamas is supposed to relinquish its weapons so that it no longer poses a threat to Israel.

It has not done so, and in its response to the US warning on Saturday, Hamas said its police forces in Gaza, "with broad popular and community support, are fulfilling their national duty in pursuing these gangs and holding them accountable".

Another clause in the ceasefire agreement states that regional partners will ensure that "Hamas, and the factions, comply with their obligations and that New Gaza poses no threat to its neighbours or its people".

Therefore, any instances or evidence of armed action by either Hamas or other factions in Gaza would be considered a violation of the ceasefire.