UN Secretary General Antonio Guterres urged Hamas to continue with the planned release of hostages on Tuesday, a day after the Palestinian militant group announced its intention to halt the exchange, Reuters reports.

"We must avoid at all costs the resumption of hostilities in Gaza that would lead to an immense tragedy," he said in a statement.

"Both sides must fully abide by their commitments in the ceasefire agreement and resume negotiations in Doha for the second phase," Guterres added.

Hamas on Monday announced it would stop releasing Israeli hostages until further notice over what it called Israeli violations of a ceasefire agreement in Gaza, raising the risk of reigniting the conflict..

US President Donald Trump said on Monday that Hamas should release all hostages held by the militant group in Gaza by midday Saturday or he would propose cancelling the Israel-Hamas ceasefire and "let hell break out."