Three Palestinians were killed as Israel pressed on with an offensive in the Gaza Strip, a bastion of Islamic hardliners where Palestinian presidential favorite Mahmud Abbas was takinghis election campaign Friday.

1\vo fighters from the military wing of Hamas - the main Islamic radical movement which is boycotting the January 9 election to replace the late Yasser Arafat - were killed by a rocket fired from an Israeli helicopter at Khan Yunis refugee camp in thesouthern Gaza Strip.

The army said it had fired at three fighters after spotting them laying explosives on a path used by

troops.

Their deaths brought the toll of Israel's operation in the area, which the army says aims to thwart Palestinian rocket and mortar firing at Gaza's settlements, to 11 killed since Wednesday. At least nine were armed militants.

On the Palestinian political front, PLO chief Mahmud Abbas was due in the Gaza Strip on a three-day visit that will see the launch of celebrations commemorating his Fatah party's 40th anniversary and politicalrallies.

The Gaza Strip is a traditional bastion of Islamist hardliners, including Hamas and its smaller rival Islamic Jihad.