GAZA (Reuters) - Israeli forces have seized a band of territory in the northern Gaza Strip in what a senior officer says is an open-ended stay to thwart Palestinian rocket attacks on southern Israel.

The creation of what Israeli Army Radio called a security zone came on the heels of a raid on a Gaza refugee camp on Thursday in which 11 Palestinians were killed, bloodshed that followed a suicide bombing that killed 15 people in Israel.

Amid the violence, Palestinian President Yasser Arafat asked Mahmoud Abbas -- who has kept a back-channel open to Israeli leaders during the past 29 months of fighting -- to be prime minister, a post international peace mediators want created.

Palestinian security sources said at least a dozen Israeli tanks and other armoured vehicles backed by helicopter gunships pushed some two kilometres (one mile) deeper into the Gaza Strip from the northern Erez border crossing early on Friday.

The force rolled up to the edge of Jabalya refugee camp, where Thursday's fighting took place, and the town of Beit Hanoun, establishing new observation points and roadblocks.

The army said in a statement the operation "was part of an attempt to...prevent the launching of Qassam rockets towards Israeli communities near the northern Gaza Strip".

Three of the makeshift rockets slammed into the southern Israeli town of Sderot on Thursday, hours after the crushing raid on Jabalya, a militant stronghold.

"We will remain for as long as is necessary..and if we decide to hold on to this territory for a long time, we will," Colonel Yoel Strick, commander of Israel's northern Gaza brigade, told Army Radio.

Recent operations in Gaza have drawn international criticism over civilian casualties and fuelled Palestinian fears that Israel's new rightist government will reoccupy all of the Strip while world attention is focused on possible U.S. war on Iraq.

In the West Bank, Israeli security forces shot dead a Palestinian gunman who they said tried to infiltrate the Jewish settlement of Hamra late on Thursday.

POWER-SHARING

On the political front, Abbas, known as a relative moderate, said he was waiting for details of the powers of prime minister before deciding whether to accept the post.

The senior Palestine Liberation Organisation official said he was not interested if the position was only symbolic. "I will respond positively or negatively after I know what powers the prime minister will have," he told Reuters.

Arafat has been under intense pressure from the United States and the European Union to reform the Palestinian Authority and appoint a powerful prime minister to take over day-to-day running of the Authority.

Israel has blamed the Authority for failing to rein in militants. Palestinian officials say the Israeli reoccupation of most of the West Bank, following suicide bombings in Israel, has made that task impossible.

Eleven Palestinians were killed and more than 140 wounded in Israel's operation in Jabalya on Thursday. Palestinian witnesses said eight of the dead were killed when an Israeli tank fired a shell at a crowd.

The army denied firing on civilians and said most deaths were caused when Palestinian militants detonated bombs meant for Israeli forces.

On Wednesday, the first Palestinian suicide bombing in two months ripped through a bus packed with high school students in the Israeil port city of Haifa. A 14-year-old American girl was among the 15 dead.

At least 1,906 Palestinians and 720 Israelis have been killed since the Palestinian uprising for statehood began in September 2000 after talks between the two sides stalled.