IRAQI forces have retaken the Salaheddin provincial government headquarters in Tikrit from the Islamic State (IS) jihadist group, a significant advance in the battle to recapture the city, officials said yesterday.

The spokesman for the Badr militia said members of the Popular Mobilisation units – pro-government paramilitary forces dominated by Iran-backed Shiite militias – took part in the fighting, after some froze offensive operations last week in response to United States-led air strikes.

“Iraqi forces cleared the government complex in Tikrit,” an army major general said, speaking on condition of anonymity.

“The government buildings have been under our control since last night (Monday).”

It is the most significant advance in Tikrit since pro-government forces launched an operation to retake the city on March 2, their largest since IS led an offensive that overran much of the country’s Sunni Arab heartland last June, according to AFP report.

Salaheddin Governor, Raad al-Juburi, confirmed that the government headquarters had been retaken, saying that Iraqi flags now flew over various recaptured buildings in the city.

Badr spokesman, Karim al-Nuri, also said that the government headquarters was recaptured, and that Popular Mobilisation members fought alongside federal police in the operation.

Key Shiite militia forces said they were halting Tikrit operations when a U.S.-led anti-IS coalition began air strikes in the area after weeks in which Iran was the main foreign partner in the operation.

The coalition strikes started last Wednesday, angering Shiite militiamen who accused Washington of attempting to hijack their victory.

The Pentagon conditioned its intervention on an enhanced role for regular government forces, and on Friday hailed the withdrawal from the fight of “those Shiite militias who are linked to, infiltrated by, (or) otherwise under the influence of Iran”.

The coalition said it carried out three strikes in the Tikrit area from Sunday to Monday, in its most recent statement on the air campaign.

After giving themselves political cover by declaring that they do not want to work with each other, both sides are still taking part in the Tikrit operation.

The main militias in the Popular Mobilisation forces have played a key role in successful operations against IS in multiple areas north of Baghdad, but they have also been accused of abuses including summary executions and destruction of property.

During a visit to Baghdad on Monday, United Nation chief, Ban Ki-moon, said that Iraq must “bring volunteer armed groups fighting in support of the government under government control”.

“Civilians freed from the brutality of Daesh should not have to then fear their liberators,” Ban said, using an Arabic acronym for IS.

Security in and around Baghdad has improved markedly during the battle against IS, in large part because the jihadists have been occupied with fighting elsewhere.