Iraqi troops backed by helicopter gunships launched an operation early Saturday aimed at dislodging Sunni militants from the northern city of Tikrit, one of two major urban centres they seized in recent weeks in a dramatic blitz across the country.

After watching much of Iraq slip out of government hands, military officials sought to portray the push that began before dawn as a significant step that puts the army back on the offensive. They said the operation includes commandos, tanks and helicopters, as well as pro-government Sunni fighters and Shiite volunteers.

Tikrit residents reported clashes on the outskirts of the city and to the south, but the extent of the fighting was unclear.

Jawad al-Bolani, a security official in the Salahuddin Operation Command, said the immediate objective is Tikrit, the hometown of former dictator Saddam Hussein and one of two major cities to fall to the al-Qaida breakaway Islamic State of Iraq and the Levant and allied Sunni militants. He said there was no concrete timeline for the operation to conclude.

Helicopter gunships conducted airstrikes before dawn on insurgents who were attacking troops at a university campus on Tikrit's northern outskirts, Iraqi military spokesman Lt. Gen. Qassim al-Moussawi said. There was no immediate word on casualties.

Government troops established a bridgehead on the sprawling campus early Friday after being ferried in by helicopter.

Mideast Iraq

People inspect buildings damaged by an Iraqi government airstrike in the northern city of Mosul. (The Associated Press)

A senior security official said there were sporadic clashes around the University of Tikrit, as well as south of the city. Iraqi forces, which are moving north toward Tikrit from the shrine city of Samarra, are making slow progress, he said on condition of anonymity because he was not authorized to brief the media.

Tikrit residents reached by telephone confirmed that air raids took place at the university around dawn Saturday. They reported fighting between the Islamic State and Iraqi forces to the southeast as well, but said militants are still in control of the city and patrolling the streets. Some residents described black smoke rising from a presidential palace complex located along the edge of the Tigris River after army helicopters opened fire on the compound.

They spoke on condition of anonymity out of concern for their safety.

Without power or water

Another Tikrit resident, Muhanad Saif al-Din, said the city has emptied out in recent days as locals flee ahead of anticipated clashes.

"Tikrit has become a ghost town because a lot of people left over the past 72 hours, fearing random aerial bombardment and possible clashes as the army advances toward the city," Saif al-Din said. "The few people who remain are afraid of possible revenge acts by Shia militiamen who are accompanying the army. We are peaceful civilians and we do not want to be victims of this struggle."

'T'ikrit has become a ghost town because a lot of people left over the past 72 hours. We are peaceful civilians and we do not want to be victims of this struggle.' - Tikrit resident

He said the city has been without power or water since Friday night.

The military also carried out three airstrikes on the insurgent held city of Mosul early Saturday. One of the air raids hit a commercial area that did not have obvious military target, residents said.

South of Baghdad, heavy clashes between security forces and Sunni insurgents killed at least 21 troops and dozens of militants, officials said.

The fighting raged for hours near the town of Jurf al-Sakhar, some 50 kilometres (30 miles) outside the capital. The town is part of a predominantly Sunni ribbon that runs just south of Baghdad.

Hospital officials confirmed the casualty figures among government troops.

All officials spoke on condition of anonymity because they were authorized to brief the media.

The Islamic State and its allies have overrun much of Iraq's Sunni heartland, a vast territory stretching west and north from Baghdad to the Jordanian and Syrian borders. After a dramatic initial push, the onslaught appears to have slowed as the militants bump up against predominantly Shiite areas stretching south from Baghdad.


Children of a Christian family, who fled from the violence in Mosul for fear of being targeted by militant group ISIS, stay at a school in Iraq's Kurdistan region. (Ahmed Jadallah/Reuters)

Iraq's large, U.S.-trained and equipped military melted away in the face of the offensive, sapping morale and public confidence in its ability to stem the militant surge — let alone claw back lost ground. If successful, the Tikrit operation could help restore a degree of faith in the security forces.

It also would provide a boost to embattled Prime Minister Nouri al-Maliki, who is fighting for his job as many former allies drop their support and Iraqis increasingly express doubts about his ability to unify the country. Al-Maliki, however, has shown little inclination publicly to step aside, and instead appears set on a third consecutive term as prime minister after his bloc won the most seats in April elections.

Alienating Sunnis

The United States and other world powers have pressed al-Maliki to reach out to the country's Sunni and Kurdish minorities and have called for a more inclusive government that can address longstanding grievances. Al-Maliki has widely been accused of monopolizing power and alienating Sunnis, who have long complained of being unfairly targeted by security forces.

Iraq is grappling with its worst crisis since the last U.S. troops withdrew in December 2011, raising the spectre of the fragmentation of the country along sectarian and ethnic lines. The United States has watched the turmoil with a wary eye. Already, Washington has already deployed 180 of 300 troops promised by President Barack Obama to assist and advise Iraqi troops.

The U.S. also has started flying armed Predator drones over Baghdad to protect American interests, a Pentagon official said Friday. He spoke on condition of anonymity because he was not authorized to discuss the new flights on the record.