BAGHDAD - Thousands of Iraqi soldiers and Shi'ite militiamen sought to seal off Islamic State fighters in Tikrit and nearby towns on Tuesday, the second day of Iraq's biggest offensive yet against a stronghold of the radical Sunni Islamist militants.
Iranian military commander Qassem Soleimani, who has helped coordinate Baghdad's counter-attacks against Islamic State since it seized much of northern Iraq in June, was overseeing at least part of the operation, witnesses told Reuters.
His presence on the frontline highlights neighboring Iran's influence over the Shi'ite fighters who have been key to containing the militants in Iraq.
Iraqi military officials said security forces backed by the Shi'ite militia known as Hashid Shaabi (Popular Mobilisation) units were advancing gradually, their progress slowed by roadside bombs and snipers.
On the southern flank of the offensive, army and police officials said government forces moving north from the city of Samarra could launch an attack on al-Dour later on Tuesday.
Soleimani, head of the Iranian Revolutionary Guards Quds Force, was directing operations on the eastern flank from a village about 55 km (35 miles) from Tikrit called Albu Rayash, captured from Islamic State two days ago.