The Israeli and US governments are slamming Hamas for postponing plans to release hostages this Saturday as part of the ceasefire in Gaza.

Israel's Defense Minister Israel Katz denounced the Islamic group's decision as a complete violation of the agreement.

Israeli military officials say they have put their troops on a higher level of readiness.

Trump warned Hamas to free all the hostages by Saturday. Speaking to reporters on Monday, he said, "As far as I'm concerned, if all of the hostages aren't returned by Saturday at 12 o'clock -- I think it's an appropriate time -- I would say, cancel it and all bets are off and let hell break out."

A senior Hamas official told Reuters on Tuesday that threats only complicate matters.

Hamas has been releasing hostages in phases since the six-week ceasefire took effect on January 19. In turn, Israel has been freeing Palestinian prisoners.

But Hamas said in a statement on Monday that a release scheduled for Saturday will not go ahead.

The group accuses Israel of violating the ceasefire by attacking residents in Gaza and failing to fully allow the flow of aid.

Hamas also said it will "keep the door open" if Israel adheres to its obligations.

The Israeli government reportedly plans to hold a cabinet meeting as early as Tuesday to discuss a response.