The panic followed the emergence of pictures showing a cloud of vapour pouring from Leningrad Nuclear Power Plant, some 50 miles from St Petersburg.
The authorities insisted that the was no radioactive leakage after a “defect” which caused a steam emission from the turbine section of the station – the most westerly in Russia – but people did not believe the “no danger” claim.
Radio Svoboda reported that in the wake of the incident on Friday locals in Sosnovy Bor started withdrawing money from their credit cards.
They said locals were in panic mode despite statements from officials that the radiation level was normal.
People had more trust in the ecologists who prepared their own statement.
They confirmed the radiation level in Sosnovy Bor was normal but said wind carried the stream away from the city towards the Gulf of Finland.
They said that didn’t mean the stream was not radioactive.
One local said: “Everyone got very worried and rushed to get iodine.”
This is seen as a protection against radiation poisoning.
There were traffic jams as residents left the area and headed for St Petersburg.
Oleg Bodrov, chairman of “Green Wolrd” ecological group said people were right not to trust denials from the authorities, with many people recalling that Soviet officials turned a blind eye to the Chernobyl nuclear catastrophe in 1986.