Israeli ground forces massed on the border of the coastal enclave for a possible invasion while Israeli warplanes went on for the fourth day with attacks on Gaza, killing 12 Palestinians. They included sisters aged 10 and 12.
Medical officials put Palestinian casualties since Israel launched its attacks on Saturday at "348 dead with more than 800 wounded."
"Three Israeli civilians and a soldier have been killed" by Palestinian rockets since the air strikes began.
Israeli media quoted Prime Minister Ehud Olmert as telling President Shimon Peres that the Gaza operation was in "the first of a several stages".
Israel has said it would allow more aid trucks into Gaza on Tuesday.
The United Nations has called for an immediate truce. But Israeli Interior Minister Meir Sheetrit said "there is no room for a ceasefire".
"The Israeli army must not stop the operation before breaking the will of the Palestinians, of Hamas, to continue to fire at Israel," he told Israel Radio.
The Israeli military "has made preparations for long weeks of action," added Matan Vilnai, a deputy defence minister, in broadcast remarks.
Hamas spokesman Fawzi Barhoum has urged Palestinian groups to respond using all available means against Israel killings, including martyrdom operations.
In Beit Hanoun, in the northern Gaza Strip, two sisters were killed in a air raid as they were taking out the trash near their home, medical workers said.
Later an Israel strike killed a security man on a headquarters in Khan Yunis and Israeli missiles flattened five ministerial buildings and a structure belonging to the Islamic University in Gaza City.
A Hamas sports centre and two training camps belonging to the group were also destroyed in the attacks, which plunged Gaza into a blackout as explosions echoed across the city.
Israeli aircraft fired missiles at the home of a senior commander in Hamas's armed wing. He was not home. Another attack targeted offices belonging to the Popular Resistance Committees group.
In Ashdod, an Israeli woman bolted from her car to seek shelter after a siren sounded, but she tripped and fell in the street, where she was killed by a rocket, local officials said.
Israel kept schools closed within a radius of about 30 km (18 miles) from the Gaza border, citing concerns about further rocket fire in a respponse to dozens of Israel bombs. Residents were told to remain indoors and on the alert for alarms.
Most Gazans in the territory of 1.5 million people, one of the most densely populated on earth, have stayed home, in rooms away from windows that could shatter in blasts from Israel air strikes.
Israel declared areas around the Gaza Strip a "closed military zone" and ordered out journalists observing a build-up of armoured forces.
Excluding the press could help Israel conceal preparations for a ground incursion following a pounding from the air that has turned buildings to rubble and left hospitals struggling to cope.
Last Mod: 30 Aralık 2008, 14:25