An Iraqi soldier launches a rocket-propelled grenade towards Islamic State militants, west of Fallujah, February 4, 2016.

Clashes between Iraqi tribesmen and the ISIS group in Fallujah have halted after the militants detained dozens of residents of the city west of Baghdad, officials said Sunday.

Tribesmen in three areas of the city “withdrew from the clashes (with ISIS), 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.

Raja Barakat, a member of the provincial council in Anbar, where Fallujah is located, said: “We now fear that the (ISIS) organization 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 jihadists in Fallujah, said ISIS 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.

ISIS, which has a reputation for extreme violence against its opponents, has already executed a large number of tribesmen elsewhere in Anbar province.

Officials said the clashes began Friday as a fight between tribesmen and Al-Hisba, ISIS members charged with enforcing religious strictures in the city.

The fighting escalated into gunbattles involving members of several tribes.

ISIS launched a sweeping offensive that overran swathes of Iraq in June 2014, but security forces and allied fighters have pushed the jihadists back with US-led air support.

Fallujah, 50 kilometers west of Baghdad, is the only Iraqi city apart from ISIS’s main hub, Mosul in the north, still under jihadist control.

The militants also hold some 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 an ISIS stronghold.

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