The leaders of France, Germany and Britain said Monday that "there can be no further delay" in negotiating a ceasefire in Gaza, warning Iran and its allies against any "further escalation" of the conflict.

The joint statement came after one of the deadliest reported Israeli strikes on the besieged Gaza Strip in more than 10 months of war.

"The fighting must end now, and all hostages still detained by Hamas must be released," French President Emmanuel Macron, German Chancellor Olaf Scholz and British Prime Minister Keir Starmer said in a joint statement.

"The people of Gaza need urgent and unfettered delivery and distribution of aid," the statement said.

"There can be no further delay."

They also welcomed the "tireless" work of Egyptian, Qatari and US mediators towards an agreement on a ceasefire and the release of hostages.

Several rounds of negotiations for a ceasefire in Gaza have failed until now, except for a one-week truce that was observed at the end of November.

International mediators have invited Israel and Hamas to resume negotiations towards a long-sought truce and hostage-release deal, as the fighting in Gaza and the killings of Iran-aligned militant leaders have sent tensions soaring across the region.

Hamas on Sunday called on US, Qatari and Egyptian mediators to implement a ceasefire plan for Gaza put forward by US President Joe Biden, instead of holding "more negotiations".

In their statement, the three European leaders also urged Iran and its allies "to refrain from attacks that would further escalate regional tensions and jeopardise the opportunity to agree a ceasefire and the release of hostages."

"They will bear responsibility for actions that jeopardise this opportunity for peace and stability. No country or nation stands to gain from a further escalation in the Middle East," said Macron, Scholz and Starmer.

In northern Gaza, an Israeli air strike on Friday killed at least 93 people at a religious school housing displaced Palestinians, according to civil defence rescuers.

The Gaza war began with Hamas's October 7 attack on southern Israel which resulted in the deaths of 1,198 people, mostly civilians, according to an AFP tally based on official Israeli figures.

Militants also seized 251 people, 111 of whom are still held captive in Gaza, including 39 the military says are dead.

Israel's retaliatory military offensive in Gaza has killed at least 39,790 people, according to the territory's health ministry, which does not provide details on civilian and militant deaths.