2:40pm UK, Wednesday May 21, 2008

A nuclear power station in Sweden has been sealed off after a worker was stopped at the entrance with a plastic bag containing traces of explosives.

Police have arrested suspect

Investigators took the man, a welder who was scheduled to do work at the Oskarshamn plant, in for questioning.

They later arrested a second man because "there is some uncertainty about who owns the bag", a spokesman said.

Plant operator OKG downplayed the incident, saying there was no threat to the safety of the plant, about 150 miles south of Stockholm.

Police said the man carried a plastic bag with an unknown amount of triacetone triperoxide, or TATP, an explosive used in the London bombings in 2007.

A plant spokesman said there were no explosives inside the bag, but traces of the explosive substance were found on the bag's handle.

A bomb squad was sent to the plant to investigate the findings.

Police set up a security perimeter with a 1,000ft (300m) radius around the plant, but workers already inside were not evacuated.

The plant continued to operate normally.

The Oskarshamn plant has three nuclear reactors, which produce about 10% of Sweden's electricity supply.