Two bombings rocked Russia's North Caucasian republic of Ingushetia on Monday morning, killing two policeman and injuring two others.

The first blast occurred at around 8:00 a.m. Moscow time (0400 GMT) when a suicide bomber detonated a car at the gate of the police headquarters of the republic's Karabulak city, said the Itar-Tass news agency.

Local policeman said another car was detonated by the remote control at the same location at around 9:10 a.m. Moscow time (0510 GMT), with no fatalities or injuries reported so far. Investigation was underway.

Meanwhile in the town of Olenegorsk in the Murmansk region, a home-made bomb of "a 200-gram TNT block, an electric detonator and an alarm clock" was found and neutralized in a parking lot near the security unit office of Russian Railways, the Interfax news agency reported.

Russia's restive North Caucasus republics, particularly Chechnya, Dagestan and Ingushetia, have been plagued by violence that particularly targeted against policemen and law enforcement officers, which local rebels take as representing the Russian authorities.

On Sunday, two handmade bombs found in the Ingush village of Ordzhonikidzevskaya were defused.

A blast earlier in the day derailed eight cars of a cargo train in Dagestan, which the authorities had linked to last week's terrorist attacks that rocked Moscow metro stations and the North Caucasian republic of Dagestan, and claimed more than 50 lives.