Fallujah is one of two Iraqi cities still controlled by ISIS, and residents -- said to number in the tens of thousands -- vastly outnumber the estimated 300 to 400 terrorists inside it, AFP reports.

But ISIS (so-called Islamic State - ISIL - Daesh) has had plenty of time to assert its control over the civilian population through arrests and public executions -- its usual means of discouraging dissent.

"Armed confrontations between the sons of the Fallujah tribes and the Daesh organisation are continuing," an army brigadier general said.

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 city's outskirts.

There have been casualties among both the tribesmen and the ISIS terrorists, the officer said.

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

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