A car bomb exploded has exploded outside a bank in southern Russia's violence-plagued Ingushetia region, injuring at least five people.

A car parked on a central street in the regional capital, Nazran, was shielding a bomb on the ground, which exploded when the owner of the car, a police officer, used a remote control to unlock the vehicle.

The officer and another policeman who was with him were seriously injured.

Three passers-by were also hurt in the explosion.

Ingushetia is a small region adjacent to war-scarred Chechnya.

A volatile region in Russia's North Caucasus, it is the site of frequent attacks targeting police authorities.