Clashes between Iraqi tribesmen and DAESH in Fallujah have halted after the militants detained dozens of residents of the city west of Baghdad, officials said Sunday. The fighting between the Sunni Arab tribesmen and DAESH in Fallujah, one of two cities it still holds in Iraq, challenges the militants' ability to maintain control. But officials said tribesmen were running short of supplies on Saturday, and DAESH has already executed a large number of opponents elsewhere in Anbar province. Tribesmen in three areas of Fallujah "withdrew from the clashes (with DAESH), fearing for the fate of the detainees", an army lieutenant colonel told AFP on condition of anonymity."The clashes stopped because of the imbalance of power and fear that the detainees would be executed," said Issa Sayir who was appointed by the Anbar governor to administer the Fallujah area. Sayir said DAESH was likely to execute Fallujah residents for their alleged "cooperation with the security forces." Raja Barakat, a member of the provincial council in Anbar, where Fallujah is located, said: "We now fear that DAESH will carry out a massacre in the city." Sayir estimated the number of detainees at around 60, while the lieutenant colonel said the figure was over 110 and a tribal leader said more than 100. Sheikh Majeed al-Juraisi, a leader in one of the tribes fighting the militants in Fallujah, said DAESH had seized the residents over the previous two days. "We hold the prime minister responsible for any massacre carried out against the people of Fallujah," Barakat said, calling for the launch of a military operation to retake the city.Both Sayir and the army officer said a military operation would be launched in the Fallujah area in coming days, but it may come too late for the detainees in the city. Officials said the clashes began Friday as a fight between tribesmen and Al-Hisba, DAESH members charged with enforcing the religious strictures of the Sunni extremist group in the city. The fighting escalated into gun battles involving members of several tribes. DAESH launched a sweeping offensive that overran swathes of Iraq in June 2014, but security forces and allied fighters have pushed the militants back with U.S.-led air support. Fallujah, 50 kilometers west of Baghdad, is the only Iraqi city apart from DAESH's main hub, Mosul in the north, still under militant control. The militants also hold other areas, including large towns such as Tal Afar and Hawijah. Anti-government fighters seized Fallujah in early 2014 during unrest that broke out after security forces demolished a protest camp in western Iraq, and it later became a DAESH stronghold. The tens of thousands of civilians in Fallujah are facing increasingly dire living conditions, and officials say DAESH is preventing people from leaving the city, which has largely been cut off by security forces. There are an estimated 300 to 400 DAESH fighters inside Fallujah, but the militants have repeatedly seized areas and defended others for extended periods despite being heavily outnumbered.