Hamas said on Thursday that Donald Trump's threats would encourage Israel to disregard the fragile ceasefire, after the US president said that unless hostages are freed, the people of Gaza would be "DEAD".

Trump's warning came hours after his administration revealed it held unprecedented direct talks with Hamas, which it proscribes as a "terrorist" group, focused on American hostages in Gaza.

Five Americans are believed to remain among the hostages – four have been confirmed dead and one, Edan Alexander, is believed to be alive.

Prime Minister Benjamin Netanyahu's office confirmed Israel was consulted and said in a statement that it "expressed its opinion" on the direct talks.

Trump said later he was "sending Israel everything it needs to finish the job" as his administration expedites billions of dollars in weapons.

"Release all of the Hostages now, not later, and immediately return all of the dead bodies of the people you murdered, or it is OVER for you," he wrote on his Truth Social platform after meeting freed hostages.

"This is your last warning! For the leadership, now is the time to leave Gaza, while you still have a chance."

Trump also warned of repercussions for Gaza as a whole, where virtually the entire population has been displaced by Israel's relentless military campaign in response to Hamas's October 7, 2023 attack.

"To the People of Gaza: A beautiful Future awaits, but not if you hold Hostages. If you do, you are DEAD!"

Hamas spokesman Hazem Qasim said Trump's words pushed Israel to disregard the terms of a ceasefire in place since January 19.

"These threats complicate matters regarding the ceasefire agreement and encourage the occupation to avoid implementing its terms," Qasim said in a statement, urging the United States to pressure Israel to enter the ceasefire's second phase. (AFP)