BAGHDAD -- Iraqi forces pressed their offensive against the Islamic State of Iraq and Syria (ISIS) on Friday, expecting to reach the outskirts of the militant-held city of Tikrit within hours, a day after the extremists reportedly "bulldozed" a famed archaeological site in the area.
The battle to wrest Tikrit -- Saddam Hussein's hometown -- from ISIS is a major test for the Iraqi forces and allied, Iran-backed Shiite militias fighting on their side.
Iraqi officials say about 30,000 men are trying to take back control of Tikrit from ISIS. CBS News correspondent Holly Williams reports the Iraqi forces are fighting alongside troops from Iran -- and an Iranian general is reportedly commanding the battle.
That's sparked fears in the U.S. about rising Iranian influence in Iraq, but many Iraqis have told Williams they welcome any help they can get, as they try to retake territory from ISIS extremists.
The governor of Salahuddin, Raed al-Jabouri, said the Iraqi forces expected to reach Tikrit later Friday. He told The Associated Press they still had not made it to Tikrit's east airport as some reports suggested.
Tikrit, 80 miles north of Baghdad, has been under the control of ISIS since June, when the Sunni militants made a lightning advance across northern Iraq, prompting Iraqi troops to flee and abandon their weapons.
On Monday, Iraqi security forces launched the large-scale operation in an effort to retake the city from the militant group, but the offensive has been stalled somewhat, with military officials saying the militants strategically lined roads leading to the city with explosives and land mines. Suicide attacks have also taken a serious toll on the Iraqi and allied forces.
Meanwhile, the Iraqi Ministry of Tourism and Antiquities said late Thursday that ISIS militants "bulldozed" the renowned archaeological site of the ancient city of Nimrud in northern Iraq.
The destruction was part of the group's campaign to enforce its violent interpretation of Islamic law, destroying ancient archaeological sites it says promoted apostasy.
The ministry's report could not be immediately independently confirmed.
Nimrud was the second capital of Assyria, an ancient kingdom that began in about 900 B.C., partially in present-day Iraq, and became a great regional power. The city, which was destroyed in 612 B.C., is located on the Tigris River just south of Iraq's second largest city, Mosul, which was captured by ISIS in June.
Earlier this week, a video emerged on militant websites showing ISIS fighters with sledgehammers destroying ancient artifacts at the museum in Mosul, Iraq's second-largest city that also fell into ISIS hands last year.
The extremists' rampage against priceless cultural artifacts has sparked global outrage.
Also Thursday, ISIS militants set fire to some oil wells outside Tikrit, an Iraqi oil official said, speaking on condition of anonymity as he was not authorized to talk to the media. The smoky fires were apparently meant to obscure targets from government bombing runs, part of the wide-scale operation that began Monday.
The Ajeel oil field, about 22 miles northeast of Tikrit, was one of at least four fields seized by the militants as a source of crude oil to sell to smugglers to finance their operations.