QALQILYAH - A Palestinian civilian and five security officials - three from the Fatah-controlled Palestinian Authority security services and two from Hamas' military wing - were killed in clashes between the two groups in this West Bank city Sunday, as Damascus-based Hamas spokesman Talal Nasser called on Palestinians to fight the PA as though they were fighting the Israeli occupation.

Ismail Radwan, a top Hamas official in Gaza, called on members of the Hamas military wing in the West Bank not to surrender to PA forces and to defend themselves against the aggression of the security services.

The Hamas call for internecine violence was unusual, and presumably includes the use of suicide bombings, since that is among the methods the group has sanctioned in its terror war on Israel.

Israeli security sources said the deaths of the two Hamas operatives seriously damaged one of the group's most dangerous cells in the West Bank. Israel has pressured the Palestinian forces to crack down on the Hamas cell as a way of keeping the Israel Defense Forces out of Qalqilyah.

Palestinian witnesses accused the PA security services of using the owner of the home in which the Hamas men had been hiding as a human shield and of preventing an ambulance crew from reaching the bodies of the Hamas men killed in the gun battle - charges similar to those often leveled against Israeli soldiers. But while a relative of the homeowner - Abed Nasser Basha, the civilian who was killed in the clashes - accused the Palestinian security forces of beginning the shootout by launching a grenade, the PA forces said the Hamas operatives opened fire after Basha's wife tossed a grenade at the PA forces. The PA forces said at least 30 hand grenades were thrown at the troops surrounding the house.

"Do you know what a human shield is?" a relative of Basha asked in a soft voice. He said the Palestinian Authority forces "entered the house opposite, which belongs to the martyr's family. They took Abed Nasser and his wife out of there and asked them to enter the house across in order to get out the wanted men. The poor people were both cancer patients, without children. As soon as he and his wife got in, they threw hand grenades at them and the exchanges of fire began."

Yesterday's gun battle represents the peak, so far, of the conflict between Hamas and Fatah in the West Bank.

The PA treated the security service officials killed in the clashes as martyrs, while Fatah attacked Hamas for urging war. Sources said the Hamas operatives refused several attempts to convince them to surrender to the PA.