Among the homes demolished was that of the family of a Palestinian bomber who blew himself up in a Tel Aviv marketplace on Monday killing three Israelis.

The homes of two other members of the Popular Front for the Liberation of Palestine, believed to be the masterminds behind Monday's bombing, were also destroyed.

Activists of several resistance groups were detained in the camp in Nablus town, Aljazeera's correspondent reported.

The correspondent added that all the gates to the town had been closed by Israeli forces, preventing anyone from entering or leaving.

Israeli forces also targeted the neighbourhoods of Ras al-Ain and al-Yasmina in the old town of Nablus.

Four killed

Earlier, Israeli troops killed four Palestinians during a raid on Nablus.

An activist of al-Aqsa Martyrs
Brigades was among those killed

Witnesses and medics said three Palestinians, including a member of al-Aqsa Martyrs Brigades, an offshoot of Yasir Arafat's Fatah group, were killed on Monday by an Israeli special unit in the old town of Nablus.

Israeli military sources said troops opened fire on fighters in the city, but put the number of Palestinians killed in the incident at two.

Earlier on Monday, Aljazeera reported that a 12-year-old Palestinian boy in the Askar refugee camp in Nablus was shot dead by Israeli troops.

Bashar Zabara died from gunshot wounds to the neck after troops opened fire at stone-throwers.

Jenin arrest

In a separate development, Israeli occupation forces arrested Fadi al-Saadi, the field leader of al-Quds Brigades, the military wing of the Islamic Jihad resistance movement.

His arrest came after troops surrounded his house in Jenin, Aljazeera's correspondent in the Palestinian territories reported.  

Three Palestinian children were injured by Israeli bullets during the confrontations in Jenin refugee camp which remains under curfew.