Israeli air strikes on Gaza 'only the first phase of assault'

Thousands of Israeli ground troops, backed by tanks and artillery, were massed along the border waiting for a signal to advance.

Israeli Prime Minister Ehud Olmert said the air attacks were "the first of several" that have been approved.

More than 360 Palestinians have been killed, most of them members of the militant Hamas ruling power but at least 64 of them were civilians.

The toll includes two sisters, aged 4 and 11, who perished in an airstrike on a rocket squad in northern Gaza today.

Hamas and other groups have pressed on with their rocket and mortar assaults, killing three Israeli civilians and a soldier and bringing a widening circle of targets into their sights with an arsenal of longer-range missiles.

The military estimated that nearly 10% of Israel's population of seven million people is now within rocket range, shifting the battles closer to Israel's heartland. Of the four Israelis killed since the operation began on Saturday, all but one were in areas that had not suffered fatalities before.

Fires blazed across the Gaza Strip's main city, Gaza City, where five government buildings were badly damaged in air attacks today. Rescue workers said 40 people were injured when warplanes dropped more than a dozen bombs on the government compound.

The campaign began with bombing security facilities, then broadened to weapons-making and storage facilities, the homes of militant field operatives, and government buildings that are the symbols of Hamas' power.

The initial wave of airstrikes took Gaza by surprise, targeting militants and Hamas security forces at key installations, often located in the midst of tiny Gaza's densely populated towns and cities.

But the government buildings targeted later were empty, as Gazans became fearful of venturing out into the streets.

The offensive began eight days after a six-month truce between Israel and the militants expired amid a barrage of Palestinian rocket fire. It comes on top of an Israeli blockade of Gaza that has largely kept all but essential goods from entering the coastal territory since Hamas violently seized control June 2007.

Israel agreed to allow 100 trucks of humanitarian aid into Gaza today as well as five ambulances from Turkey.

A Jordanian diplomat said 21 Jordanian army doctors and four field hospitals would be allowed to enter tomorrow.

Israel's navy turned back a boatload of pro-Palestinian protesters who had hoped to enter Gaza to demonstrate against the Israeli blockade.

So far planes and unmanned drones have dominated Israel's military operation. But the army has moved up thousands of infantry, dozens of tanks and artillery pieces. With the air force knocking off target after target, the big question looming over the operation is whether it will expand to include ground forces. The border area was declared a closed military zone yesterday, drawing an information fog over operations in the area.

A spokesman for Mr Olmert would not comment on the prospects for a ground operation, but said Israel would "continue keeping the pressure up on the Hamas military machine."

"This operation will continue until a new security reality can be created in the south, and those hundreds of thousands of Israelis who live in fear of Hamas rockets no longer have to live in that fear," he said.

Short of reoccupying Gaza, however, it was unlikely any amount of Israeli firepower could permanently stop rocket attacks. Past operations all failed to do so.

• Miliband urges EU to call for Israel-Palestine ceasefire

• More anti-Israeli protests expected across UK

• Online poll: Is the Israeli bombardment of Gaza justified?

• Terrified witnesses to 'all-out war'