US welcomes Iran's 'positive' role in offensive to retake Tikrit

Iran's role in an Iraqi military offensive to recapture Tikrit could be positive as long as it does not fuel sectarian divisions in the country, the US military's top officer said on Tuesday.

General Martin Dempsey, chairman of the US Joint Chiefs of Staff, told senators that Iran is acting in a more open manner this week as Iraqi forces push to retake Tikrit from Islamic State jihadists.

"This is the most overt conduct of Iranian support," Dempsey said, which came "in the form of artillery" and other aid.

"Frankly, it would only be a problem if it resulted in sectarianism," he told the Senate Armed Services Committee.

US commanders rarely discuss Iran's activities in Iraq in public, stressing that Washington does not coordinate with Tehran's military in any way - even though the two foes see IS as a common enemy.

US officials have pressed the Shiite-led government in Baghdad to reach out to the country's alienated Sunni community and worry that Shiite militia could persecute the Sunni community as they roll back IS.

Officials in Baghdad say a 30,000-strong force has been mobilized to take back Tikrit in an assault launched on Monday.

Dempsey said Shiite militia account for about two-thirds of the force, while Iraqi government army troops make up the remainder.

If the Iraqi army and Shiite fighters "perform in a credible way" and defeat the extremists in Tikrit, "then it will, in the main, have been a positive thing in terms of the counter-ISIL campaign", Dempsey said, using an alternative acronym for Islamic State.

Iraqi forces closed in on Tikrit on Tuesday, their progress slowed by jihadist snipers and booby traps, on the second day of Baghdad's largest operation yet against IS.

Outnumbered and outgunned, the extremists who have held Tikrit since June 2014 have been resorting to guerrilla tactics to disrupt the government's advance.

"They are using urban warfare and snipers, so we are advancing in a cautious and delicate way, and we need more time," said a lieutenant general on the ground.

Iraqi forces are moving on Tikrit from three directions.

AP - AFP