* Sides trade blows again in build-up to ceasefire

* Netanyahu convened top ministers after Biden call

* Almost 250 dead in fiercest hostilities in years (Adds new strikes, shelling)

By Nidal al-Mughrabi and Dan Williams

Israeli Prime Minister Benjamin Netanyahu’s office said his security cabinet had voted unanimously in favour of a “mutual and unconditional” Gaza truce proposed by Egypt, but added that the hour of implementation had yet to be agreed.

Within minutes of the announcements, in the countdown to the ceasefire, the sides were trading blows again. Sirens warned of incoming rockets in Israeli border communities, and a Reuters reporter heard an air strike in Gaza.

There was no immediate word of casualties.

Amid growing global alarm at the bloodshed, U.S. President Joe Biden urged Netanyahu on Wednesday to seek de-escalation, while Egypt, Qatar and the United Nations ventured mediation.

A Hamas official told Reuters the ceasefire would be “mutual and simultaneous”.

Egyptian President Abdel Fattah al-Sisi had ordered two security delegations into Israel and the Palestinian Territories to work towards upholding the ceasefire, Egyptian state TV reported. It also confirmed the 2 a.m. hour.

Rocket attacks by Hamas and allied Islamic Jihad had resumed after an eight-hour pause earlier on Thursday, as Israel continued shelling that it said aimed to destroy the factions’ military capabilities and deter them from future confrontation after the current conflict.

Israeli Defence Minister Benny Gantz said on Twitter that the Gaza offensive had yielded “unprecedented military gains”.

Since the fighting began on May 10, health officials in Gaza say 232 Palestinians, including 65 children, have been killed and more than 1,900 wounded in aerial bombardments. Israel says it has killed at least 160 combatants in Gaza.

Authorities put the death toll in Israel at 12, with hundreds of people treated for injuries in rocket attacks that have caused panic and sent people rushing into shelters.

On Thursday, Biden discussed Gaza with Egyptian President Abdel Fattah al-Sisi and the White House said reports of moves toward a ceasefire were “encouraging”.

U.N. spokesman Stephane Dujarric confirmed that U.N. Middle East Envoy Tor Wennesland is in Qatar, adding: “We are actively engaged with all the relevant parties for an immediate ceasefire.”

(Editing by Angus MacSwan, Philippa Fletcher, Giles Elgood and Andrew Heavens)