Gaza City/Tel Aviv  - Israel's cabinet approved Sunday plans to call up more than 6,000 reserve soldiers, raising the possibility that the two-day old offensive against the radical Hamas movement in in the Gaza Strip could include a ground operation as well as air strikes.

The Israel Air Force, however, kept up its attacks on the enclave, hitting, among other targets, Gaza City's main security compound, which houses a central prison and several security force headquarters.

Four people were killed in the attack, bringing to 285 the number of people, more than half of them militants, killed in the Israeli operation which began Saturday in response to massive rocket barrages on southern Israel since a six-month truce with the militant organizations ended. Over 900 people have been wounded.

Aircraft also attacked shortly after midnight the Hamas-run al- Aqsa satellite channel, completely destroying its four-story building. Minutes later, the channel resumed broadcasting from unknown studios prepared as an alternative in advance.

In the late afternoon Israel struck at the so-called Philadelphi corridor, a narrow strip of land along the Gaza border with Egypt. Witnesses said aircraft fired missiles at the open ground, in an effort to destroy tunnels which run under the border and are used for smuggling goods and weapons.

By late afternoon Sunday, Israel had launched more than 30 attacks on Gaza since midnight, after the air force had hit over 100 targets when the offensive began Saturday.

Palestinian President Mahmoud Abbas, Hamas' bitter political rival, said Sunday he had contacted the Islamist organization and urged its leaders to maintain the truce with Israel in order to prevent a crisis.

"We contacted Hamas officials directly, we called them on the phone and urged them not to end the ceasefire with Israel," he said while on a visit to Cairo.

Militants in the Gaza Strip who vowed to avenge the Israeli attacks succeeded in launching 40 rockets and mortars at Israel.

Two of the missiles struck south of the port city of Ashdod, over 39 kilometres north of the Strip, and the furthest rockets fired from the salient have yet landed in Israel.

Two Grad missiles also hit the resort city of Ashkelon, which lies around 14 kilometres north of the Strip, and which has become an increasing target for the missile strikes.

There were no fatalities reported from the missile and mortar strikes.

The latest launchings bring to over 100 the number of rockets and mortar shells fired at the Jewish state since the operation against Hamas began, and to around 300 the number fired since a six- month truce between Israel and the Gazan militias ended 10 days ago, on December 19.

Egyptian Foreign Minister Ahmed Abul Gheit meanwhile accused Hamas Sunday of preventing casualties from entering Egypt for treatment.

Hamas spokesman Fawzi Barhoom said the accusations were "totally untrue," but at the same time said Hamas "cannot accept sending the wounded and waiting for them to come back in boxes and shrouds."

Israel officials have said that for the moment the offensive against Hamas in the enclave was being conducted solely though airpower, and any decision to send in the armour and foot- soldiers would be made later, according to operational assessments.

However, reports late Sunday afternoon said tanks and armoured personnel carriers were also taking up positions along the border.

In another indication that the operation, as Israeli leaders from Prime Minister Ehud Olmert down have indicated, could be lengthy, the government Sunday also approved plans to operate a "special situation" status for communities adjacent to the Gaza Strip, which for example allows the Home Front Command to instruct local authorities to act to close down factories or keep people in their homes.

Three of the people killed in the Israel air strike on the security compound were prisoners; the fourth was a guard. Those prisoners who survived scrambled over the rubble and fled, pursued by some Hamas guards.

Hamas spokesman Fawzi Barhoum said the prisoners were not evacuated in advance "because we were told by the ICRC (International Committee for the Red Cross) that the compound was exempt from bombing," (dpa)