Israeli aircraft have attacked Gaza for a third day, as speculation mounts of a full ground offensive.
Troops have massed along the Gaza border and Israel got a strong boost from Washington this afternoon, which blamed Hamas for the violence.
'In order for the violence to stop, Hamas must stop firing rockets into Israel and agree to respect a sustainable and durable ceasefire,' White House spokesman Gordon Johndroe said.
But anger over the mammoth bombing campaign has spiralled in the Muslim world, and efforts to hold talks between Syria and Israel have been suspended because of the air assault.
The Israeli blitz, unleashed on Saturday in retaliation for ongoing rocket and mortar fire from Gaza, has killed at least 345 Palestinians and wounded more than 1,400 others.
At least 57 civilians, including 21 children, have died as a result of the bombardment, a UN spokesman said.
Since Saturday, Gaza militants have fired more than 250 rockets and mortar rounds into Israel, killing two people.
The European Union has described Israel's continuing air strikes on Gaza as 'unacceptable' and called on both sides to halt military actions.
As Israeli tanks massed on the Gaza border overnight, the army declared the area a closed military zone - a move that in the past has been followed by ground operations in the Palestinian enclave.
Amid mounting international calls for a halt to the violence, Israel allowed the passage of humanitarian aid into Gaza - where most of the 1.5 million population depends on foreign aid.
Hamas militants have responded to the air strikes with renewed rocket attacks on Israel.
An Israeli Arab was killed and eight other people were wounded when one of the projectiles slammed into a construction site in the southern city of Ashkelon, 13km north of Gaza.
Jabaliya attack
Four girls from the same family, aged from one to 12 years old, died in fresh Israeli raids overnight. They died in an air raid in the northern town of Jabaliya that targeted a mosque near their home. Two boys were later killed in a strike on the southern city of Rafah.
China and Japan joined the growing international chorus for a halt to the violence, which has also included Britain, France and Russia. Protests took place in many European capitals at the weekend.
Hamas has lashed out at the world for not doing enough to end the blitz. Israel is 'committing a holocaust as the whole world watches and doesn't lift a finger to stop it,' Hamas spokesman Fawzi Barhum said.
Amid vows by Israeli Defence Minister Ehud Barak to expand the air blitz and to send in ground troops if necessary, the Israeli cabinet yesterday gave the green light to call up 6,500 reserve soldiers.
Protest held at Israeli Embassy
More than 150 people turned out at the Israeli Embassy in Dublin to protest at the ongoing military offensive in Gaza.
The protest heard calls for the Irish government to break diplomatic relations with Israel and to use its influence in Europe to cease trading with Israel.
The protest was organised by Ireland's Palestinian Community, the Irish anti-war movement and The Ireland-Palestine Solidarity group.
Minister for Foreign Affairs Micheál Martin has again issued a strong condemnation of the Israeli air-strikes.
The chairwoman of the Ireland Palestine Solidarity Campaign, Marie Crawley, welcomed Mr Martin's condemnation, but called on the Government to provide funds for emergency medical supplies.
Meanwhile Derek Graham, a Co Mayo man who is a director of the Free Gaza Movement, is among a group of activists on a boat that was attempting to take three tons of emergency medical supplies into Gaza today.
