Baghdad, March 13 (IANS): Iraqi security forces on Thursday continued their offensive to free Tikrit, the capital city of Salahudin province, from the Islamic State (IS) militants, a security source said.

After two days of fierce clashes, Iraqi troops and government-backed Shia and Sunni militias gained some ground by seizing parts of the city, which is located some 170 km north of the Iraqi capital Baghdad, the source told Xinhua.

The troops supported by dozens of tanks, armoured vehicles, heavy artillery shelling and aircraft, were moving slowly and cautiously amid heavy clashes with the militants, including a large number of IS snipers, the source said.

Defence Minister Khaled al-Obeidi told reporters near Tikrit that the Iraqi forces and the allied militias, known as Hashid al-Shaabi, were moving to the second phase of the plan to liberate Tikrit on Thursday, "which will be decisive to free the city from the IS militants".

The minister, however, did not specify the time for the next phase of battle.