US President Donald Trump has given Hamas a deadline to accept the US peace plan for Gaza or face "all hell".
Trump wrote on his Truth Social platform on Friday that a deal must be reached by 6:00 p.m. Washington time (22:00 GMT) on Sunday.
The plan proposes an immediate cessation of fighting and the release within 72 hours of 20 live Israeli hostages held by Hamas, as well as the bodies of hostages thought to be dead, in exchange for hundreds of detained Gazans.
Arab and Turkish mediators are pressuring Hamas for a positive response to the proposal, but a senior Hamas figure has said the armed group is likely to reject it.
"If this LAST CHANCE deal is not made, all HELL, like no one has ever seen before, will break out against Hamas. THERE WILL BE PEACE IN THE MIDDLE EAST ONE WAY OR ANOTHER," Trump wrote in the Truth Social post.
The BBC understands that mediators have contacted the head of Hamas's military wing in Gaza, who has hinted that he does not agree with the new US ceasefire plan.
It is thought that some of Hamas' political leadership in Qatar are open to accepting it with changes - but have found their influence limited as they have no control over the hostages held by the group.
Another obstacle for some in Hamas is that the plan requires them to hand over all hostages within the first 72 hours of the ceasefire - thus giving them their only bargaining chip.
It is believed that 48 hostages are still being held in Palestinian territory by the armed group, only 20 of whom are thought to be alive.
The Israeli military launched a campaign in Gaza in response to the Hamas-led attack on southern Israel on October 7, 2023, in which about 1,200 people were killed and 251 others were taken hostage.
At least 66,288 people have been killed in Israeli attacks on Gaza since then, according to the Hamas-run territory's health ministry.