Mushrooms containing traces of radiation, believed to be from Chernobyl, have been stopped from being imported into France.
The shipment of more than three tonnes of mushrooms from Belarus contained traces of cesium 137, a waste product of nuclear reactors, French authorities said.
It was discovered passing through Frankfurt, Germany but did not pose a health threat, according to the nuclear safety body IRSN.
The incident comes just a week after Russia denied a nuclear accident had occurred in the country after it recorded “extremely high” traces of a radioactive isotope.
Russia’s weather service measured pollution of ruthenium-106 at 1,000 times normal levels in the Ural mountains.
An IRSN spokesman said the contaminated mushrooms had “no link with the ruthenium-106 pollution”.
“As the mushrooms came from Belarus, it is very likely the contamination originated in Chernobyl,” the spokesman said.
Chernobyl in Ukraine is just south of the Belarus border and was the site of a major nuclear disaster in 1986.
Cesium 137, which has a 30-year half-life, is still widely found in the areas around Chernobyl.
The IRSN spokesman said eating tens of kilos of the Belarus mushrooms would expose a consumer to radioactivity levels similar to natural ambient radioactivity during a whole year.
He added that there had been no health risk for the customs officials, even if they had touched the mushrooms with their bare hands.