A reported accident at a nuclear power plant in central Russia spread panic on Friday, as residents rushed to buy radiation antidotes despite official assurances that the malfunction was a minor glitch.

"As a result of turbine malfunction, block number two of Balakovskaya nuclear power station underwent an emergency shutdown at 13:24 on November 4," said a press release from Russia's federal nuclear agency.

"There was no increase of radioactivity," it said. "The event does not endanger security and under international standards of nuclear events is classified as zero."