Iraqi helicopter gunships struck suspected insurgent positions in Tikrit on Sunday as part of a government offensive to retake the predominantly Sunni hometown of former dictator Saddam Hussein from Sunni militants led by the al-Qaida breakaway Islamic State of Iraq and the Levant, residents and officials said.

The Iraqi military launched its push to wrest back Tikrit, a hotbed of antipathy toward Iraq's Shiite-led government, on Saturday with a multi-pronged assault spearheaded by ground troops backed by tanks and helicopters. Security officials said the army is coordinating its campaign with the United States.

Tikrit is one of two major urban centers that fell to insurgents earlier this month during their lightning offensive across the country's north and west.

The insurgents appeared to have repelled the military's initial push for Tikrit, and remained in control of the city on Sunday, but clashes were taking place in the northern neighborhood of Qadissiyah.