FALLUJAH, Iraq (AFP) - Masked gunmen remained in control of Iraq's Fallujah on Wednesday even as traffic police returned to the city's streets after a jihadist group urged Sunnis to keep fighting the Shiite-led government.

Fallujah and parts of the Anbar provincial capital Ramadi farther west have been outside government hands for days - the first time militants have exercised such open control in major cities since the height of the insurgency that followed the 2003 US-led invasion.

Earlier on Wednesday, two areas of Fallujah saw brief clashes and shelling, witnesses said, but it was not immediately clear who was involved in the fighting.

The traffic police, whose sole responsibility is directing vehicles and controlling intersections, were back on the streets in several parts of central Fallujah, an Agence France-Presse journalist reported.

They were apparently back on duty with the blessing of the gunmen, whose allegiance was not immediately clear.

The gunmen were deployed in areas around the edge of the city, at the entrances of neighbourhoods, and on bridges - including one from which the bodies of American contractors were infamously hung in 2004, prompting the first of two US assaults on Fallujah that year.

Some shops in the city reopened, and light traffic returned to the streets.

But the city still faces the threat of an assault by soldiers deployed nearby.

The Al-Qaeda-linked Islamic State of Iraq and the Levant (ISIL) has been active in Fallujah, but so have anti-government tribes.

The security forces have meanwhile recruited their own tribal allies in the fighting that has raged in Anbar province for more than a week and killed over 250 people.

Near the provincial capital Ramadi, soldiers backed by helicopters battled gunmen in the Khaldiyah area, a police captain said.

The fighting came after the release late Tuesday of an audio recording purportedly from ISIL spokesman Abu Mohammed al-Adnani urging Sunnis to continue fighting the Shiite-led government.