Taliban militants have stormed a jail outside the central Afghan city of Ghazni, killing at least four policemen and freeing more than 350 prisoners.

The deputy provincial governor of Ghazni province Mohammad Ali Ahmadi said one militant blew himself up at the prison gates, allowing others to force open jail cells.

The attackers were well-organised and wearing uniforms, he said.

The Taliban confirmed it had carried out the early morning attack.

Both Taliban spokesman Zabihullah Mujahid and the deputy governor confirmed that three of the attackers were killed.

The deputy governor said seven police officers were also injured. He said only 80 prisoners were left inside the prison.

It was not immediately clear who the prisoners who escaped were, nor where they had gone.

Mr Ahmadi said he did not reject the possibility the attackers had had help from inside the jail. He added that most of the prisoners were Taliban, with some petty criminals and drug addicts.

Local officials told the BBC's Afghan service that as the attackers made their way through the jail, the prisoners did not initially realise the attackers were Taliban and not police because of their uniforms.

The jail is about 5km (3 miles) outside Ghazni city, which is about 120km from the capital, Kabul.

In 2011, nearly 500 prisoners - including many Taliban insurgents - escaped from a jail in Kandahar city, after a tunnel hundreds of metres long was dug from the outside.

Afghan jail breaks

June 2008: More than 900 prisoners escape from Sarposa prison in Kandahar after a suicide bomber blasted open the gates.

July 2010: Nineteen prisoners escape after a blast at a prison in Farah province.

November 2009: Twelve prisoners escape after tunnelling out of a jail from their cells in Farah.

April 2011: More than 470 inmates escape from a Kandahar jail through through a 360m (1,180ft) tunnel dug from outside.