In this Friday, July 17, 2015 photo, smoke rises after a bombing as Iraqi security forces backed by Shiite and Sunni pro-government fighters attack Islamic State group position in Fallujah, 40 miles west of Baghdad, Iraq.

Sunni Arab tribesmen battled militants of the ISIS group in their Fallujah stronghold for a second day Saturday in a major blow to the jihadists in Iraq, officials said.

Fallujah is one of two Iraqi cities still controlled by ISIS, but residents — said to number in the tens of thousands — vastly outnumber the estimated 300 to 400 jihadists inside it.

ISIS has had plenty of time to assert its control over the civilian population and has carried out large numbers of arrests and public executions in the city.

“Armed confrontations between the sons of the Fallujah tribes and the Daesh organization are continuing,” an army brigadier general said, using an Arabic acronym for ISIS.

The clashes are taking place in Al-Jolan in northwest Fallujah and Nazal in the centre, the officer said, adding that the army was shelling ISIS positions on the outskirts.

There have been casualties among both the tribesmen and the jihadists, the officer said, without giving a number.

Tribal leader Sheikh Majeed al-Juraisi said that fighting was continuing in both the centre and north of Fallujah.

The tribesmen “are beginning to run out of supplies and need the support of the government,” he added.

There is “fear that they will completely run out and afterwards the Daesh organization will arrest and massacre them.”

In 2014 and 2015, ISIS executed dozens of members of the Albu Nimr tribe, which opposed the jihadists’ seizure of most of Anbar province, including Fallujah.

Saadun Obaid al-Shaalan, who was elected by a local council to administer the Fallujah area, confirmed that the fighting was ongoing, saying that tribesmen had posted snipers on rooftops in the Al-Askari area of east Fallujah.

He said the tribesmen were in need of supplies and “we are trying to obtain that support” from the government.

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

Members of the Al-Juraisat, Al-Mahamda and Al-Halabsa tribes joined the fighting as it escalated.

Fallujah, which lies about 50 kilometres (30 miles) west of Baghdad, is the only Iraqi city apart from ISIS’s main northern hub Mosul still under jihadist control.

Several large town in the north are also held by the jihadists, including Tal Afar and Hawijah.

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

Tribesmen have played a key role in holding the jihadists back in several areas, including Haditha in Anbar, Amerli in Salaheddin province and Dhuluiyah in Diyala.

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