At least 21 people were injured in a powerful blast near an enclosure of local a racecourse in the Russian Caucasian city of Nalchik on Saturday.

The incident took place in Nalchik, which is the capital of Russia's Caucasus republic of Kabardino-Balkaria and has witnessed Muslim militants' raid at the local security office buildings few years ago.

According to ITAR-TASS republic's former Interior Minister Hachim Shogenov, who is said to be behind the elimination of the local Islamist militant leadership, was present in the VIP enclosure, while rest of the local leadership was on city tour on the May Day celebrated in post-Communist Russia as the Labour and Spring Day.

On March 29, two suspected Chechen female suicide bombers blew themselves up on packed metro trains in central Moscow killing at least 39 people and wounding 63 others.

Though no organisation claimed responsibility for the deadly attacks during morning rush hour, chief of the federal security service blamed militant groups active in Russia's volatile North Caucasus region (Chechnya) for the strikes.

On March 31, two suicide bombers, including one in police uniform, set off powerful blasts in Russia's volatile North Caucasus region of Dagestan, killing at least 12 people and injuring 27, just a couple of days after the terror attacks on Moscow metro claimed 39 lives.