NABLUS, West Bank - Fatah gunmen on Monday released a top Hamas official after holding him hostage for two days and displaying him in an al-Qaida like video, but factional tensions remained high as pro-Fatah militants torched stores owned by Hamas sympathizers.

The firebombings marked the first time that militants have targeted civilians in the West Bank, widening the political violence in the Palestinian areas.

Until this week, most of the violence centred on the Gaza Strip, where more than 30 people have been killed in clashes between forces loyal to the rival groups. Now Fatah militants in the West Bank have begun retaliating for Hamas attacks in Gaza.

At a news conference in Gaza after sundown Monday, Hamas official Fawzi Barhoum said Fatah was trying to violently oust the Hamas-led Palestinian government. "We will not allow those seeking a coup to drag our people into the flames of a civil war, and will never let them drag our people into a family war,'' Barhoum said.

Another Hamas official, Ismail Radwan, called on Palestinians to use their weapons against Israel, not each other.

On Monday evening, former Finance Minister Salam Fayyad, a political independent who served in the Fatah-led cabinet, said gunmen fired on his office earlier in the day. Police investigating the shooting said one of Fayyad's bodyguards accidentally discharged his weapon.

The kidnapping of Mahdi al-Hanbali, a top Hamas official in the West Bank's commercial centre of Nablus, was the strongest sign yet that fighting could soon reach the West Bank.

Al-Hanbali, unshaven and his shoes covered in mud, was hoisted on the shoulders of his supporters inside the city council after his release. He said he was not hurt in captivity, but he appeared nervous during a news conference, twitching his lips and fidgeting.

"They treated me well. They didn't ask me for anything special,'' he told reporters. He thanked Palestinian President Mahmoud Abbas, of Fatah, and other officials for working for his release.

His captors released a video on Sunday showing him surrounded by masked gunmen. In the video, resembling tactics used by Iraqi insurgents, the captors threatened widespread attacks against Hamas targets.

Fatah militants, in return, threatened more attacks against Hamas.

"Any attack on a Fatah member or a Fatah institution will have a response in the West Bank, and a violent one too,'' Nasr al-Kharaz, a Fatah militant, told the Associated Press. Hamas' stronghold is in Gaza, while Fatah is stronger in the West Bank.

Fatah and Hamas have been in a vicious power struggle since the Islamic group defeated Fatah in parliamentary elections last year. Hamas controls the legislature and most government functions, while Fatah holds the powerful presidency.

Abbas, a moderate, favours peace talks with Israel, while Hamas rejects the Jewish state's right to exist, despite an international boycott against its government. Abbas has urged Hamas to join Fatah in a more moderate unity government, but months of negotiations collapsed in late November, sparking the latest round of factional violence.

In the West Bank town of Ramallah on Monday, Fatah militants set fire to six stores belonging to Hamas supporters, security officials said. A large clothing store and a money changing shop were destroyed, the officials said.

In the town of el-Bireh, outside Ramallah, militants fired shots at the house of the Hamas-allied mayor, the officials said, speaking on condition of anonymity because they were not authorized to speak to the media. No one was hurt.