The Hamas on Tuesday banned public prayers in the Gaza Strip, moving to halt growing dissent by supporters of the rival Fatah movement. Fatah supporters have held public prayers over the past two weeks in downtown Gaza City that have quickly turned into violent demonstrations against Hamas's rule in Gaza. The demonstrations occurred on Fridays, when Muslims traditionally gather for prayers. "The government decided to ban any gathering under the pretext of performing Friday prayers," Hamas announced. "They went beyond the aim of prayers and they were used for the purpose of chaos, strife, rioting, and practicing terrorism. The government will take all necessary measures to support security and public order in Gaza." After weeks of silence, Fatah sympathizers have become increasingly bold in expressing displeasure with Hamas rule. In the first public prayer session last month, Fatah worshippers marched to Hamas security compounds and threw stones, prompting security men to fire in the air to disperse the crowd. Last week, Hamas forces beat and detained dozens of Fatah members. Hamas said it continues to hold about 60 "subverters," many of whom have been unable to post the $250 bail. Ahead of the ban, the Muslim Scholars League, a group of local mosque leaders, issued a religious edict in support of halting the outdoor prayers. Marwan Abu Rass, the league's chairman, said the outdoor prayers were taboo because they were being held for political reasons, not religious necessity. Fatah leaders say they have been forced to hold the public prayers in downtown Gaza City because they no longer feel welcome in Gaza's mosques. Jamila Saidom, a senior Fatah member in Gaza, called the ban an "escalation" meant to halt opposition. "This is a pretext to give anyone who goes out to pray a hard time," she said. In a separate challenge to Hamas, Gaza's 900-member firefighting force began an open-ended strike on Tuesday. Saker Mujahed, commander of the Civil Defense Force, ordered his men to stop work early Tuesday, claiming Hamas has taken over its buildings and equipment. Mujahed, a Fatah supporter, issued the order from his West Bank headquarters. Hamas officials condemned the strike, saying it endangered public safety. "The aim of this move is to destroy and burn Gaza," said Ihab al-Ghusain, a Hamas security spokesman. He said his forces stepped in to fill the place of striking workers. Also Tuesday, a previously unknown group apparently affiliated with Fatah claimed responsibility for the bombing of a car of a Hamas activist and four other blasts that have targeted the Islamic group this week. The bombings, which caused no injuries, appeared to be a new tactic in Fatah-Hamas tensions in Gaza. A statement posted on the independent Gaza-based Ramattan news Web site said the explosion, and four other blasts this week, were retaliation for "Hamas crimes." It was signed "The Brigades of Martyrs of Security Agencies" apparently in reference to members of the Fatah-affiliated security forces who were killed when Hamas wrested control of Gaza. Hamas spokesman Fawzi Barhoum blamed the West-Bank-based Fatah leadership for the blasts. Meanwhile, deposed Prime Minister Ismail Haniyeh called for international mediation to restore relations with Fatah. "We ... welcome any Arab, Islamic and international mediation to patch the rift between the Palestinians," he said after the weekly meeting of his deposed government. Abbas has rejected dialogue with Hamas until it relinquishes control of Gaza.