BEIT HANOUN, Gaza Strip (AP) Responding to rocket fire, Israeli troops and tanks swept through three Palestinian towns and the outskirts of a refugee camp yesterday in the biggest operation in the Gaza Strip since violence broke out nearly 17 months ago. Five Palestinians, including a civilian, were killed in exchanges of fire that began before dawn.

Islamic militants said they will keep firing rockets at Israel, despite Israeli warnings that such attacks will trigger more large-scale operations.

In the West Bank, there were exchanges of fire after two Israeli tanks and several other vehicles entered the town of Jenin, Palestinians said. The Israeli military spokesman"s office said it had no knowledge of an incursion in Jenin.

In a clash late yesterday with Israeli soldiers near a Jewish settlement in Gaza, a Palestinian gunman was killed and three others escaped, Israel Radio reported. Israeli and Palestinian officials had no comment.

The moves came amid increasing tension within the Palestinian Authority and exasperation in Israel, whose persistent military efforts have failed to prevent the Palestinians from using an ever-expanding arsenal of weapons including the Qassam-2 rocket, which puts Israeli cities within range.

After nightfall, Israeli forces were pulling out of Beit Hanoun, a town in the northeast corner of the Gaza Strip. They left Beit Lahiya, a small part of the nearby Jebalya refugee camp and Dir al-Balah, a town in central Gaza, several hours after entering.