U.S. and Iraqi authorities view Mosul, the provincial capital of Ninawa, as one of the last remaining al-Qaida strongholds in Iraq. Iraqi Prime Minister Nouri al-Maliki ordered a military crackdown in the northern city in May.

The gains from these operations, however, have disintegrated as militant groups re-entered the city and gunmen reportedly are roaming the streets in force, the Iraqi daily Azzaman reported.

Ninawa officials said there was an insufficient number of Iraqi troops to maintain security following operations in May.

Officials said they are also concerned about the presence of the Kurdish Peshmerga force, which guards their political districts in the largely Arab city.