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Palestinian gunmen forced a Hamas commander to his knees and shot him to death early Wednesday outside the courthouse where he worked as an Islamic judge, escalating factional tensions in the Gaza Strip and prompting the Palestinian prime minister to cut short a trip abroad.

The death came two days after three young sons of a Fatah-allied Palestinian intelligence officer were killed in a drive-by shooting, sparking renewed conflict between the rival Hamas and Fatah factions. The violence has reduced chances for a unity government and pushed the two sides closer to civil war.

Palestinian security officials said the slain man was Bassam al-Fara, 30, a judge at the Islamic court and a Hamas commander who belongs to the largest clan in the town of Khan Younis.

In a statement faxed to reporters, Hamas accused a Fatah "death squad" for al-Fara's death.

Fawzi Barhoum, a Hamas spokesman, said the dead man had been a field commander in Hamas' military wing and a prominent figure in the militant Islamic group. He gave no further details about al-Fara's militant activities but pledged to hunt down the killers. "Hamas is not going to forget the blood of its members," Barhoum said.

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Fatah spokesman Tawfik Abu Khoussa rejected the accusations. "We condemn all acts of anarchy whatever may be behind them. We call on the brothers in Hamas to stop firing accusations before the investigation," he said.

In Sudan, Prime Minister Ismail Haniyeh, a top Hamas official, said he would return to Gaza on Thursday, cutting short a trip to Arab and Muslim countries, including Iran and Syria. Haniyeh left Gaza on Nov. 28 on what was expected to be a monthlong trip.

"We need the prime minister to be here now to resolve the internal problems," said Haniyeh's political adviser, Ahmed Youssef.

Haniyeh dismissed fears of the violence in Gaza escalating into a civil war.

"We want to assure you that words such as 'civil war' don't exist in our dictionary. They don't exist in our makeup, in our culture," Haniyeh said in Khartoum. "We will protect the national unity of the Palestinian people and we will thwart any attempt to instigate an inter-Palestinian struggle."

Witnesses to the shooting Wednesday said four gunmen calmly ate breakfast at a food stand as they waited for al-Fara outside the courthouse. When al-Fara emerged from a taxi, three of the men grabbed him and forced him onto his knees, while the fourth shot him. The attack left the sidewalk riddled with bullet holes. The witnesses declined to be identified, fearing for their safety.

Dozens of people gathered at the scene and Palestinian security set up roadblocks. Hamas militants also set up their own roadblocks throughout town, searching for the shooters.

About 1,000 Fatah loyalists, about half of them uniformed security personnel, marched through Gaza to the residence of President Mahmoud Abbas of Fatah.

"We tell Abu Mazen the time has come to exercise your powers and stop this farce," said Othman Shalouf, an officer in the National Security Service. Abbas is also known as Abu Mazen.

Some of the protesters fired in the air, but there were no clashes with Hamas militiamen they passed on their route. One demonstrator shouted appeals for Palestinian unity over a loudspeaker.

Students of the al-Azhar university joined the procession, carrying pictures of the three boys killed Monday, as well as Fatah security men killed in internal clashes.

Fatah and Hamas have been locked in a power struggle since Hamas ousted Fatah in parliamentary elections. More than 40 Gazans have died in battles between the two groups since Hamas took power in March.

Seeking to end the standoff, Abbas has been trying to persuade Hamas to join Fatah in a national unity government. But the talks broke down late last month. Tensions heightened after Abbas announced plans over the weekend to call early elections, drawing Hamas accusations that he is plotting a coup.

The latest round of violence was sparked by the deaths Monday of the three young sons of Baha Balousheh, an intelligence officer and Fatah loyalist who helped lead a crackdown on Hamas a decade ago. Balousheh, who was not in the car, escaped two previous Hamas assassination attempts.

Hamas denied involvement in the boys' deaths.

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