Jerusalem, Jan. 15 : The United Nations on Thursday expressed its outrage against Israel after it targeted its headquarters in the Gaza Strip, injuring three of its employees.

Chris Gunness of the UN Relief and Works Agency (UNRWA) told Sky News that hundreds of people were taking refuge inside the compound when it was hit by "three white phosphorus" shells.

The weapons burn at extremely high temperatures, starting fires that cannot be put out with fire extinguishers.

Gunness confirmed that a blaze is raging in one of the buildings housing hundreds of tons of food aid due to be pushed out today.

Gaza - The central United Nations compound in the Gaza Strip has been

Gaza City - Israeli ground troops pushed deep into southern Gaza City Thursday, advancing as far as 1.5 kilometres from the city centre amid heavy tank shelling, residents said.

The ground forces were "very close" to the city's Islamic University and its United Nations headquarters, a local Deutsche Presse-Agentur dpa correspondent said, adding that he was sheltering with his family inside a home in the central Rimal neighbourhood with the troops fighting nearby.

Backed by tanks firing large numbers of shells, the Israeli troops, concentrating in the southern Tel el-Hawa neighbourhood just south of Rimal, fought heavy battles with local militants.

Dubai - A spokesman for the Palestinian Islamist movement told the Arabic television channel al-Arabiya on Thursday that the organization would not enter a ceasefire agreement with Israel amid intense diplomatic efforts to bring the two sides together.

Mohammed Nassal, a member of the Damascus-based Hamas political bureau, told the channel that Hamas would not enter an unlimited ceasefire as Israel has demanded.

"We are ultimately a resistance movement. While Palestinian land is occupied, we have the right to undertake resistance," he said.

Tel Aviv - Palestinian militants fired a fresh volley of rockets into southern Israel from the Gaza Strip Thursday morning, after a lull in the attacks during the night.

At least seven rockets landed in Israeli territory, most of them in open areas and two in the town of Ofakim, Israel Radio reported.

The Israeli military has reported a significant reduction in the number of rocket and mortar attacks compared to the earlier days of Israel's Gaza offensive - launched December 27 in a bid to end more than seven years of such attacks from Gaza into southern Israel.

Tel Aviv/Gaza City - Israel kept up its air, ground and sea attacks in Gaza Thursday, as its representative was heading for Cairo to debate an Egyptian truce initiative, and the UN and Germany's top diplomats were in the region to also push for a truce.

UN Secretary-General Ban ki Moon and German Foreign Minister Frank-Walter Steinmeier were each due to hold talks with Israeli leaders in Jerusalem and Tel Aviv Thursday, meeting Israeli President Shimon Peres, caretaker Prime Minister Ehud Olmert and Foreign Minister Tzipi Livni.