Iraqi forces have withdrawn from the militant-held northern Iraqi city of Tikrit after a new push to retake the city met heavy resistance, a soldier who fought in the battle said.

Government troops and allied Shia volunteer fighters were forced to retreat just before sunset to a base 4km south after coming under heavy mortar shelling and sniper fire.

The attempt to retake Tikrit, which fell on 12 June to Sunni insurgents led by the Islamic State group, began two-and-a-half weeks ago.

No fighting was reported in Tikrit this morning, according to residents.

Tikrit lies 160km north of Baghdad.

It is a stronghold of loyalists of the late dictator Saddam Hussein and ex-army officers who joined forces with Islamic State to take over large parts of north and west Iraq last month.

The military had attacked from the village of Awja, 8km south of the city, and the initial fighting occurred in the southern part of the city.

The army retook Awja, the birthplace of Saddam, on the night of 3 July, and has been trying to push north since.

The Islamic State controls territory immediately to the north of the city.

The group posted photos on an affiliated Twitter feed of what it called "the Tikrit battle" of dead fighters from the battle that it referred to as "martyrs" and of tanks and trucks with mounted machine guns flying the trademark black and white Islamist flag.