Iraqi army and Kurdish politicians question Iran's involvement in Iraq

The Iraqi army, supported by Shiite militiamen, is laying "full siege" to the city of Tikrit where Islamic State militants are now surrounded, according to Iraq's defence minister on Monday. 

The Iraqi military - backed by at least 20,000 Shiite fighters - has been fighting to regain control of Saddam Hussein's hometown of Tikrit, one of several predominantly Sunni towns to fall to IS militants last year.

Operations to recapture Tikrit have been on hold for nearly a week, with Khaled al-Obeidi, the Iraqi defence minister, saying the army was trying to minimise casualties by not rushing the final assault.

"The terrorists are surrounded inside the city and their morale is low. When the right moment comes, we will storm the city without any resistance or losses," he told Al Jazeera.

The Tikrit siege is one of the first major operations in which the US-led coalition is not taking part, with US officials saying they were not asked to participate.

Possible divisions

Against the backdrop of the Tikrit siege, the head of a Shiite armed group, Hadi al-Ameri, pointed to a possible divide between the Iraqi army and Shiite units. 

While the US has been working to train Iraqi military brigades, it has not worked with the Shiite groups due to their closeness with Iran.

John Brennan, CIA director, said having the leader of Iran's elite Quds Force directing Iraqi forces against IS is complicating the US mission.

In an interview with Fox News Sunday, Brennan described General Qassem Soleimani as being "very aggressive and active" in advising the Shiite militias, adding that he "wouldn't consider Iran an ally right now inside Iraq".

Iranian advisers have played a prominent role on the front lines of Iraq's Salahuddin province.

Kurdish politicians question Iran

Strengthening claims against Iran, Kurdish authorities in Iraq accused Tehran of sending 30,000 soldiers and military experts to fight IS.

Shakhawan Abdullah, the head of Iraq's parliamentary security and defence committee, told Al Jazeera on Sunday that Iranian soldiers were operating in a number of Iraqi cities and fighting on Iraqi soil.

Abdullah said Iran's presence went beyond military advisers and experts, and that Iranians were fighting under the banner of the Popular Mobilisation Forces.

The Popular Mobilisation Forces is an umbrella organisation of Shiite armed groups composed of around 100,000 fighters.

Iran has repeatedly denied sending soldiers to Iraq despite claims by the US.

In August, Iran was accused of sending hundreds of soldiers to retake the town of Jawlala from IS, while in December it was alleged that an Iranian F-4 fighter struck IS targets in the province of Diyala.