Israel's prime minister cleared the way Wednesday to expand an offensive against the Palestinians' governing Hamas movement aimed at freeing an abducted soldier and ending rocket attacks from Gaza.

In fresh violence, Hamas gunmen skirmished with Israeli forces stationed near the northern Gaza town of Beit Hanoun, witnesses said.

Militants said they fired at least two anti-tank rockets, hitting an Israeli tank and a bulldozer. The Israeli army said it was not aware of any anti-tank rocket fire. There were no immediate reports of casualties.

Political sources said the Israeli army was discussing establishing a buffer zone in northern Gaza to halt cross-border rocket fire after the Hamas armed wing fired a missile into the coastal city of Ashkelon for the first time on Tuesday.

A spokesman for Prime Minister Ehud Olmert said no decision had been taken.

"Given the abduction and continued ballistic salvoes, including the (rocket) launched at Ashkelon, the rules of the game in dealing with the Palestinian Authority and Hamas must be changed," a statement from Olmert's office said.

The statement said Olmert's security cabinet had approved strikes against Hamas in Gaza and the occupied West Bank, focusing on "institutions and infrastructure facilitating terrorism."

It also approved stepped-up attacks on rocket crews in Gaza.

Israel quit Gaza last year after 38 years of occupation, but launched its offensive following the abduction of Corporal Gilad Shalit by militant groups including the Hamas armed wing in a cross-border raid from Gaza on June 25.

The army has already sent tanks and troops inside the northern border but stopped short of a major push into towns. It entered the south last week, establishing a static position in Gaza's disused international airport.

Israel has also detained eight Hamas cabinet members and nearly two dozen lawmakers in the West Bank.

Olmert has called Tuesday's missile strike on Ashkelon an "escalation without precedent."

The upgraded rocket traveled 12 kilometers from Gaza. No one was hurt but it was the first time a major Israeli city has been hit. Previous rocket salvoes targeted small border towns.

Meanwhile, Palestinian security sources said that the Israeli army has reopened Erez crossing, allowing foreigners and journalists to leave the Gaza Strip, but denying entry from Israel into the strip.

There was also news that Israel has asked Palestinian President Mahmoud Abbas to leave the Gaza Strip where he has been stuck since the abduction of the Israeli soldier.

Three Palestinian militant groups, including governing Hamas' armed wing, the Popular Resistance Committees and its offshoot the Islamic Army, claimed responsibility for the abduction.

However, Chief Palestinian Negotiator Saeb Erekat has denied the news and told Xinhua that Abbas is staying in Gaza and will stay there until the end of the crisis.

(China Daily, Xinhua News Agency, July 6, 2006)