Israeli tanks and troops have moved into a Palestinian refugee camp in the West Bank city of Tulkarm in a hunt for militants who attacked a kibbutz over the weekend.

The attack killed five Israelis, including a mother and her two young sons.

Palestinian sources and eyewitnesses say that about 30 tanks, armoured troop carriers and jeeps entered the camp at about 0300 local time (0100 GMT).

The Israeli army told the Associated Press news agency that the troops arrested three men before withdrawing several hours later.

Earlier, Israeli security sources said the army would strike at the Tulkarm and Nablus areas of the West Bank because of suspected links with the kibbutz gun attack.

Israeli Prime Minister Ariel Sharon and Defence Minister Shaul Mofaz visited the kibbutz on Monday.

Palestinian leader Yasser Arafat has said he will appoint a committee to investigate the attack.

Pressure on Sharon

The attack also happened at the start of an election campaign, as Israeli politicians vie to appear patriotic and tough on terrorism.

Mr Sharon is under pressure to take strong action after the new foreign minister, Binyamin Netanyahu - who is challenging him for leadership of the right-wing Likud Party - repeated his call for Mr Arafat to be exiled.

The attack coincided with a visit by an American envoy, David Satterfield, who is seeking to revive the stalled peace process.

The killings took place inside Israel itself, not in one of the controversial settlements in the West Bank, and targeted a kibbutz which had a history of left-wing politics and co-operation with its Arab neighbours.