The attacker blew up his car at a checkpoint at Khassaviurt, in northern Dagestan, a statement said. It said the blast left a crater that was two metres in diameter (two yards) and 1.5 metres deep.

The North Caucasus, the southwest Russian region where Dagestan is located, witnesses near-daily violence that officials blame on militants.

Dagestan is currently the most unstable region in the Northern Caucasus, with rebels staging attacks against the pro-Kremlin local authorities almost every day.