Suicide bombers have killed around 30 people in Kandahar City, Afghanistan.

Four different parts of the southern city were targeted in the attack, in which 50 other people were wounded.

Authorities in the area have suggested the attacks may have been carried out to help facilitate a prison break, which had been rumoured to occur at the same time as the bombings.

The biggest bomb strike was in front of the city's main prison, while another happened outside the police headquarters.

Apart from casualties, the two other attacks caused some shops and houses to collapse.

President Karzai, speaking to the media said his authorities were aware of the rumours that the prison was going to be hit and took action to protect it.

A similar incident in 2008, involving an exploding fuel truck, saw 1,200 prisoners, including Taliban militants, escape.

Kandahar is the largest city in the Taliban's southern stronghold and is is southern Afghanistan's main commercial centre.