Iraqi forces and militia fighters have seized major government buildings in the heart of the city of Tikrit after fierce battles with Isis militants.

Iraqi media reported Wednesday that the Iraqi Security Forces (ISF) are now in control of the Sunni city's military hospital and a number of other government buildings close to the city centre.

The Levantine Group, a risk consultancy that is live mapping the Iraqi advance, said that Isis were gradually being pushed out of the city centre.

The offensive is made up of tens of thousands of government soldiers and Iranian-backed Shia militias that have been pushing towards the Isis stronghold of Mosul since last week.

Iranian military commanders have also played a prominent role in the attack, including General Qassam Suleimani, head of Iran's Revolutionary Guard.

Tikrit, the home city of former dictator Saddam Hussein, lies on the main highway between Baghdad and Mosul and will be the first Sunni city liberated from Isis if it falls.

On Tuesday, the ISF and militia fighters captured towns on the outskirts of Tikrit including Al-Alam, but made slow progress clearing the streets of mines and booby traps.

"ISIS militants have planted an estimated 6,000 mines inside Tikrit, slowing down the joint operation to enter and retake the city," Ahmed Abdulla al-Jubouri, Iraq's provincial affairs minister, told Kurdish media today.

The New York Times reported last night that the pro-government forces had advanced within yards of central buildings.

These included the city's provincial council and the office of its governor as well as surrounding the palaces of Saddam Hussein on the edge of town.

Elsewhere in Iraq it was reported that ISIS had detonated seven car bombs in the western city of Ramadi, which is close to Fallujah, the Islamist's Iraqi heartland.