The Israel Air Force on Tuesday evening unleashed a massive strike on a network of Hamas-dug tunnels in the southern Gaza Strip near the Philadephi Route, according to Palestinian sources.

IAF planes attacked dozens of the tunnels, which Hamas had used to smuggle weapons and militants between Egypt and the Gaza Strip, the army said in a statement.

The army said that the IAF struck 30 additional targets over the course of Tuesday, including seven Grad and five Qassam rocket launchers, rocket launching cells, rocket launching sites, weapons manufacturing facilities, Hamas outposts and armed terror operatives.

The IAF kept up a relentless string of attacks on the Hamas-ruled Gaza Strip on Tuesday, smashing a government complex, security installations and the home of a top militant commander.

According to a Military Intelligence assessment, the air offensive has destroyed a third of the Hamas rocket arsenal, Channel 10 television reported.

Meanwhile, thousands of Israel Defense Forces ground troops, backed by tanks and artillery, massed along the Gaza border and waited for a signal to attack.

More than 380 Palestinians have been killed since the air force began its operation on Saturday, most of them members of Hamas security forces but at least 64 of them civilians, according to UN figures.

Tuesday's death toll included two sisters, aged 4 and 11, who perished in an airstrike on a rocket squad in northern Gaza on Tuesday.

Palestinian witnesses said that Israeli missiles flattened five ministerial buildings and a structure belonging to the Islamic University in Gaza City.

One Israeli attack targeted a house in the Jabaliya refugee camp, killing seven people, but the Hamas activist was not there, Hamas security and relatives said. Another hit the Jabaliya home of Abdel-Karim Jaber, a Hamas political figure who is a senior administrator at Gaza's Islamic University.

He was not at home and it wasn't immediately clear if anyone was hurt in the strike.

In another air assault, an Islamic Jihad commander was killed as he was walking near his house, said Abu Hamza, a spokesman for Islamic Jihad's military wing.

Israel's airstrikes on more than 325 sites since midday Saturday reduced dozens of buildings to rubble, overwhelmed hospitals with wounded and filled Gaza's deserted streets with smoke and fire. The IDF said Israeli naval vessels had also bombarded targets from the sea.

On Monday, aircraft pulverized a house next to the home of Hamas Premier Ismail Haniyeh, a security compound and a five-story building at a university closely linked to the Islamic group - all symbols of Hamas strength in the coastal territory it has ruled since June 2007.

Egypt to treat 11 wounded Palestinians

An Egyptian medical official says 11 Palestinians have been ferried from the border with Gaza to a hospital in the capital Cairo because they are in critical condition.

Ahmed Abdel-Nabi, deputy manager of the Nasser Institute hospital, said Tuesday that most will require surgery.

Since Israel attacked the Gaza strip with air strikes, killing over 300 people and injuring hundreds more in response to Hamas rocket fire, Egypt has accepted 36 injured Palestinians.

Palestinian health officials said Monday there were at least 150 serious cases in the overburdened Palestinian hospitals.

Most of those accepted are being treated in the 250-bed El-Arish hospital near the Gaza border which lacks sophisticated medical equipment.