The French nuclear safety agency says it thinks an apparently minor accident at a Russian facility caused a recent spike in radioactivity in the air over much of Europe.

The Institute for Radiological Protection and Nuclear Safety says the release of the isotope Ruthenium-106 posed no health or environmental risks to European countries.

The agency said the "plausible zone of release" was between the Volga River and the Ural Mountains.

It suggested random checks on food imports from the region as a precaution.

In a report released Thursday based on monitoring in multiple countries, IRSN said the Ruthenium appeared to come from an accident involving nuclear fuel or production of radioactive material.

The report says the radioactivity peaked in late September and early October, and is no longer detected in the atmosphere.