MOSCOW — A powerful bomb blast ripped through an outdoor market in central Russia crowded with early afternoon shoppers Friday, killing eight and wounding 37 according to the Ministry of Emergency Situations.

There was no immediate claim of responsibility for the blast in Samara, Russia's sixth-biggest city, or indications of whether it was connected to terrorists or one of the commercial disputes that often turn violent in Russia.

Emergency workers had initially said the blast at the Kirov market in Samara, some 800 kilometres southeast of Moscow, was due to the explosion of two gas canisters used for cooking, and they ruled out foul play, but regional prosecutor Alexander Yefremov later said it was a bomb made of plastic explosive.

Russian television broadcasts showed bloodied bodies lying under tarpaulins or laid on pallets, corrugated metal kiosks torn apart by the blast and the ground strewn with brightly coloured clothing, shoes and other goods sold at the market.

"The explosion was very powerful, and the place was packed with people," said Timofei Zakharchenko, a spokesman for the Samara branch of the Emergency Situations Ministry.

He said eight people were confirmed dead and 37 were injured. The Interfax news agency said a higher toll cited earlier by news agencies was due to the fact that some victims had been counted more than once in the confusion following the blast.

The explosive was placed on the back wall of one of the kiosks, the ITAR-Tass news agency said. Interfax said that the epicentre of the explosion was near a railway that ran alongside the market.

A series of market explosions have plagued the North Caucasus city of Vladikavkaz in recent years, including a May 1999 bombing that killed 55 people at the central market and a 2001 blast at the same market that killed six. Two men convicted in the latter bombing allegedly were paid to set it off by rebels from the nearby separatist republic of Chechnya, where Russian troops and rebels have been fighting for nearly five years.

But commercial and criminal disputes often turn violent in Russia with car bombings and street shootings. A 2000 bombing that killed 13 people in a kiosk-lined underground passage in Moscow was initially blamed on Chechen rebels, but authorities later said they also suspected a turf battle between businessmen or criminal gangs.