Canadian forces and other NATO troops have been deployed to Kandahar after the main prison in the southern Afghan city was attacked by militants, setting all prisoners free.

Maj. Jay Janzen, a spokesman for the Canadian Forces, said troops were on the scene and had established a security perimeter in the vicinity.

"We believe the situation is under control,” Janzen said, without elaborating on the details.

Around 10 p.m., Taliban insurgents drove a car filled with explosives up to Sarposa prison's main gate and detonated it, destroying the gate and killing all police officers in the vicinity, the CBC's Paul Hunter reported from Kandahar.

Afghan officials also said Taliban insurgents fired several rockets at parts of the prison.

A Taliban spokesman said 30 insurgents on motorbikes and two suicide bombers attacked the prison. Qari Yousef Ahmadi also claimed that hundreds of Taliban prisoners were freed in the assault.

Taleban militants have attacked a jail in the Afghan city of Kandahar and set hundreds of inmates free, reports say.

Wali Karzai, brother of President Hamid Karzai and Kandahar provincial council president, told the BBC 1,000 inmates were in the jail and all escaped.

Of the inmates, about 350 were believed to be Taleban.

There have been a number of casualties among security forces. A lorry bomb blew open the main gates of the jail and about 40 Taleban stormed inside.

A state of emergency has been declared in Kandahar city.

Police and troops are on the streets and all residents have been ordered not to leave their homes.