GAZA CITY, Gaza Strip (AP) – Hamas defied President Mahmoud Abbas’ decree Saturday that its paramilitary unit is illegal, saying it will fight any attempt to disband the force in an increasingly bloody faceoff between the Islamic militant group and Abbas’ Fatah party.

Three more Hamas supporters were killed in the factional fighting that is threatening to plunge the Palestinian territories into civil war.

The two groups have been wrangling over power since Hamas defeated Fatah in parliamentary elections a year ago and gained control over most Palestinian government functions. However, Fatah continued to dominate security forces and last spring, Hamas formed its own security unit known as the Executive Force, recruiting many former members of its military wing.

Tensions between the rival security forces erupted into large-scale fighting last month. Since then, more than two dozen people have been killed.

Abbas outlawed the Executive Force on Saturday, two days after Hamas gunmen stormed the home of a top pro-Fatah security commander and killed him and seven bodyguards. It was the deadliest battle yet during the recent wave of infighting.

Abbas’ office said the decision was made “in light of continued security chaos and assassinations of a number of our fighters … and in light of the failure of existing agencies and security apparatuses in imposing law and order and protecting the security of the citizens.”

The statement did not explicitly threaten force, saying only that the Hamas militia “will be dealt with accordingly as long as it is not immediately folded into legal security forces.”

Abbas also confirmed the U.S. was sending aid to boost Palestinian security forces loyal to him. President Bush is asking Congress to provide $83 million for those forces, U.S. officials said Friday.

Abbas’ office said late Saturday he spoke to Secretary of State Condoleezza Rice on the current situation ahead of her upcoming visit. The U.S. views Abbas, a moderate who seeks peace talks with Israel, as a legitimate negotiating partner. But Washington, along with Israel and the European Union consider Hamas, which is committed to Israel’s destruction, a terrorist group.

Egyptian President Hosni Mubarak called on the Palestinians to halt their fighting. Egypt frequently mediates between opposing Palestinian factions.

Abbas claims authority over most Palestinian security forces, but Hamas controls the Interior Ministry, which also has security responsibilities. The various forces were formed more than a decade ago by the late Yasser Arafat, who created rivalries to keep potential challengers weak.

After years of corruption and fighting with Israel, the forces have become largely ineffective, resulting in widespread lawlessness, particularly in the Gaza Strip.

In the Hamas stronghold of Gaza, leaders of the group defiantly rejected Abbas’ decree.

Interior Ministry spokesman Khaled Abu Hilal said Abbas was giving the green light for attacks on Hamas security men and that the unit would “deal firmly” with anyone who attacks it. He also announced plans to double the size of the Executive Force, which now has 6,000 men, compared with some 18,000 security men aligned with Fatah.

Prime Minister Ismail Haniyeh of Hamas accused Abbas of trying to deepen the rift between the two camps.

“I’m completely convinced that there are those who don’t want the Palestinian scene to enjoy calm and stability or to create the appropriate atmosphere for starting serious and deep dialogue aimed at reaching a national unity government,” he said.

Abbas has been urging Hamas to join Fatah in a coalition in an effort to end international sanctions against the Hamas-led government that have crippled the Palestinian economy. But months of negotiations broke down in late November, sparking the latest wave of violence.

Previous attempts by Abbas to disband the Hamas militia or integrate it into existing security units have failed.

Late Saturday, three members of a pro-Hamas family were slain by gunmen from a rival clan considered to be Fatah supporters, witnesses and family members said. The same Fatah family has kidnapped about 10 Hamas supporters in recent days, Hamas officials said.

Hamas’ radio station in Gaza said one of the dead was a member of the Executive Force.

Also Saturday, gunmen in the West Bank stopped the car of Nablus’ deputy mayor, Mahdi al-Khamdali of Hamas, and took him away in another car, security officials said. There was no immediate claim of responsibility, but the officials said they believed the kidnappers were Fatah supporters.

A pro-Hamas university professor in Nablus was shot and seriously wounded by gunmen who fired at his home late Saturday, security officials said.

AP-ES-01-06-07 1933EST