Iraqi forces loyal to Prime Minister Nouri al-Maliki have launched an airborne assault on Tikrit, the hometown of Saddam Hussein which was captured by Islamic State of Iraq and the Levant (Isis) militants in their lightning charge through northern Iraq.

The forces seized control of the city's university, the location of which is of strategic value, according to officials.

Security forces flew into the city by helicopter and engaged with Isis fighters before capturing the university campus.

The capture of the education institute is viewed as a way to retake the city after it was overrun by Sunni militants earlier this month.

"All of Tikrit is in the hands of the militants," an Iraqi police colonel said at the time of the city's capture.

Hundreds of prisoners were freed by the Islamist group as security forces lost the battle to thwart militants in heavy clashes near the Salaheddin provincial government headquarters in the city centre.

Tikrit is the hometown of fallen former dictator Saddam Hussein and lies 150km (95 miles) north of Baghdad and 223km (139 miles) south of Mosul, Iraq's second city, which has also been captured by the group.