Suspected explosives seized at nuclear plant in Sweden

Bjorn Larsson Rosvall / Scanpix via EPA

A view of the Ringhals nuclear power plant in Varberg, Sweden, on Thursday.

STOCKHOLM -- The threat level was raised at all of Sweden's nuclear sites after security personnel found suspected explosives during a routine vehicle search at a nuclear power station on Wednesday, according to reports.

"In the afternoon, a suspected explosive was discovered in a truck on its way in to Ringhals' operating facility," the plant's operator Vattenfall said in a statement. "A sample of the material was sent during the evening to the Swedish National Laboratory of Forensic Science for analysis."

The Local reported cited an official as saying the material had been placed near a fire extinguisher "under the first step onto the truck." It was said to be the size of a "small fist," according to The Local.

"The assessment is that the situation is under control," police spokesman Lars Grimbeck told MarketWatch.

Ringhals' four reactors, on the southwest coast of Sweden near the city of Gothenburg, produce nearly 20 percent of the country's electricity.

State-owned Vattenfall has a 70 percent stake in the plant and Germany's owns nearly 30 percent.

Reuters contributed to this report.

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