Suspected Taliban militants blasted into a prison in the southern Afghan city of Kandahar late Friday, freeing a number of prisoners and killing two guards, officials said.

A number of prisoners have been taken away from the prison. We don't know exactly how many people were in the prison and how many prisoners have managed to escape," said Justice Minister Sarwar Danish, adding that an investigation was underway.

Officials said that that there were around 400 Taliban prisoners in the jail at the time along with hundreds of other criminal inmates.

The main entrance of the jail was rocked by a huge explosion followed by gunfire, causing a large part of the facility's front wall to collapse, added Danish.

"The information we have so far is that around 10:00 pm there was a very strong explosion at the entrance gate of Kandahar main prison followed by an armed attack inside the prison," Danish said.

Afghan security forces had entered the prison and had retaken control, Danish said.

"A big part of the front wall of the prison has collapsed. Two prison guards have been martyred, an unknown number are wounded and there might be some prison guards under the rubble which I don't have a figure for."

A police official said that the explosion was "apparently a car bomb, followed by an assault by a number of Taliban with small arms fire and rocket-propelled grenades."

"They went into the prison and freed a number of political prisoners. There's still sporadic fire inside the prison, I don't know how many people attacked and how many prisoners were freed," the official said.

An Afghan intelligence official said separately there had been at least one explosion and that some prisoners were believed to have escaped.

Afghan and foreign troops were outside the prison, the intelligence official said.

Kandahar jail was the scene of a mass hunger strike by hundreds of inmates in May, during which 47 of the prisoners sewed their lips shut after complaining they had been tortured and denied fair trials.

Prisoners including Al-Qaeda and Taliban militants rioted at the country's main Pul-e-Charki jail in Kabul in February 2006, taking control of a block and leaving several people injured.

Five guards and four inmates with suspected links to Al-Qaeda and the Taliban died during a stand-off at the same jail in Kabul in December 2004.

The Taliban have been battling the new government of President Hamid Karzai since they were toppled from power in a US-led operation for failing to hand over Al-Qaeda chief Osama bin Laden in 2001.