Two suicide car bombers blew themselves up at checkpoints on a highway near oilfields in the southern Iraqi province of Basra on Friday, killing several people, police sources and an interior ministry spokesman said.

Iraq's South Oil Company said there was no disruption to operations but oil police were put on maximum alert in response to the attack, officials said.

Bomb attacks in southern Iraq, where the bulk of the country's oil is produced, are relatively rare.

The victims included two soldiers, a traffic policeman and an unknown number of civilians traveling in a bus.

The first blast took place at the Rumeila checkpoint and the second around one km away at another checkpoint called al-Sadra, an interior ministry spokesman said.