The bomb attack at a horse race in Russia's North Caucasus region claimed its first victim Saturday when one of those injured died in hospital, while the official injured toll rose to 29, news agencies said.

The attack took place at a hippodrome in the city of Nalchik, capital of Russia's North Caucasus region of Kabardino-Balkaria.

Saidli Shibzukhov, a war veteran born in 1906, died during surgery in hospital, an emergency ministry spokesman said.

Twenty-three other people who were injured in the bombing remain in Nalchik hospitals, the spokesman told Interfax news agency.

Among those injured was Kabardino-Balkaria Culture Minister Ruslan Firov, a source from the local emergency ministry said.

The bomb exploded near a VIP box during the race, according to a ITAR-TASS report.

A law enforcement source told the RIA Novosti news agency the explosive was a time bomb, equivalent to about 5 kg of TNT.

The ministry officials said the attack was aimed at civilians and was designed to hit as many people as possible.

The explosion could be revenge of extremists for the elimination of underground bandits' leaders and aimed at destabilizing the situation in the republic during the May Day celebration, the Kabardino-Balkar president Arsen Kanokov told the Itar-Tass.

No organization has claimed responsibility for the blast yet.

Russian President Dmitry Medvedev said in a telephone conversation with Kanokov he had instructed the Federal Security Service (FSB) and the Interior Ministry to investigate the bombing and ensure public security in Kabardino-Balkaria.

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

A suicide car bomber attacked a police checkpoint in North Caucasus Republic of Dagestan on Thursday, killing two policemen and injuring 17 others.