New Ceasefire

GAZA, Dec 19 (Reuters) - Gun battles between Hamas forces and those loyal to Palestinian President Mahmoud Abbas of Fatah raged on Tuesday in the Gaza Strip, where at least six fighters were killed, reviving fears of civil war.

Hamas and Fatah security chiefs later agreed to withdraw their forces from the streets, a senior Palestinian official said. A previous ceasefire deal broke down within 24 hours and it was unclear whether this one, brokered by Egyptian mediators, would hold.

The day's death toll was the highest since internal fighting intensified over the weekend. Four of the six were killed in street battles. The bodies of two of Abbas's security men were found dead hours after their abduction, hospital officials said.

Concerned events were spinning out of control, Western and Arab nations urged a halt to the fighting.

The internal violence, the worst in a decade, has escalated since Abbas called for early elections on Saturday to try to break a political deadlock with the Hamas government. Hamas has described his move as a "coup".

Palestinian Prime Minister Ismail Haniyeh, a senior Hamas leader, reiterated in a speech broadcast live on television that the movement rejected Abbas's election call. Hamas has said it would boycott any polls.

Haniyeh accused the United States of spearheading efforts to bring down his government

In Gaza City, civilians fled for safety and some shops closed as gunmen fought running battles with automatic weapons and rocket-propelled grenades.

"This is madness," said taxi driver Adel Mohammad-Ali, 40. "The streets are divided between Hamas and Fatah gunmen. You never know who is who."

U.S. Secretary of State Condoleezza Rice said the violence had to stop. "We hope that there will in fact be a ceasefire between the parties. That is very important," Rice told Al Arabiya television.

Regional powerhouse Saudi Arabia urged Palestinians to overcome their differences.

Israeli Prime Minister Ehud Olmert travelled to Jordan for unannounced talks with King Abdullah.

The Hamas-run Interior Ministry said Egyptian security officials had brokered a deal for members of rival security services to leave the streets and return to their headquarters.

The deal required various factions to also free hostages they were holding, ministry spokesman Khaled Abu Hilal said.

COMMITTED TO ELECTIONS

Abbas said on Monday he was committed to early elections but left the door open for the formation of a Fatah-Hamas coalition with a "technocrat" cabinet that could satisfy the West.

Hamas and Fatah tried for months to form a unity government to end a power struggle, but talks foundered, essentially over Hamas's unwillingness to soften its stance toward Israel. Hamas beat Fatah in January elections.

The rival factions blamed each other for the surge in violence in which four Fatah and two Hamas fighters were killed.

Fatah sources said the two abducted security men had been "executed" by a Hamas-led police unit. A Hamas police spokesman denied the force had abducted or killed anyone.

At least a dozen people were wounded, including five children who were caught in the crossfire.

In the West Bank city of Nablus, an Islamic court judge aligned with Hamas was shot in the legs by unidentified gunmen.