A suicide blast near a university in southern Afghanistan has killed at least seven civilians and left another 23 wounded, according to officials.

The attack happened in Kandahar city in front of Kandahar University, around two kilometres from the former compound of Taliban leader Mullah Omar, which is now used as a base by US special forces, provincial police chief General Abdul Razaq told AFP news agency on Monday.

"A suicide bomber in a car packed with explosives hit a civilian mini-bus while crossing the street, as a result of
the blast seven people were martyred, 23 others were wounded -- eight of them in a critical condition," said Raziq.

The provincial governor's spokesman Jawed Faisal confirmed the death toll and said most of the victims were Afghans working at the US base.

In a statement on twitter, the provincial governor's office said students at the university were on vacation at the time of the "cowardly attack".

The target of the blast is not known, but high-ranking government officials study at the university in the evenings.

Attacks in Kandahar, considered to be the birthplace of the Taliban, have been increasing recently.

The attack comes a day after a gunman wearing an Afghan police uniform killed three British soldiers in Helmand province.

The UK defence ministry has confirmed that all three NATO soldiers at the checkpoint were British.

The attacker was arrested after the incident.