STOCKHOLM, Sweden – Swedish police arrested two maintenance workers on suspicion of sabotage after they tried to enter a nuclear plant Wednesday with traces of the explosive used in the London terror bombings in 2005, officials said.
Police experts with bomb-sniffing dogs were dispatched to search the Oskarshamn nuclear power plant and examine the substance, believed to be triacetone triperoxide, or TATP, which can be extremely dangerous even in tiny amounts.
"It's not something you use at home," Anders Osterberg, a spokesman for plant operator OKG, told The Associated Press. "We're not dealing with toys here."
The two men were contractors hired to perform maintenance work on one of the plant's three reactors, which was shut down on May 11 for an annual checkup, plant spokesman Roger Bergman said. One of them was initially described as a welder, but plant officials later said his occupation was not clear.
Police did not release their identities, but said one was born in 1955 and the other in 1962. The older suspect was "known to police" from prior investigations, police spokesman Sven-Erik Karlsson told AP. He declined to give details.
The men were brought in for questioning after they arrived for work early Wednesday at the power plant, located about 150 miles (250 kilometers) south of Stockholm. The men were stopped because one of them was carrying a plastic bag that was found to contain traces of TATP in a security check, police said.
Bergman said the second man was arrested because "there is some uncertainty about who owns the bag."
Both were arrested after questioning on suspicion of preparing sabotage, a crime punishable under Swedish law by up to two years in prison, according to the Justice Ministry.
Plant operator OKG said the incident did not pose a threat to the nuclear facility, which remained in operation.
Osterberg, the OKG spokesman, said the plastic bag contained toiletries, but a small amount of the explosive substance was found on the bag's handle, suggesting it may have rubbed off from the man's hands.
TATP is highly explosive, and a tiny amount would be enough to blow off a person's hand, said Svante Karlsson, a weapons expert at the Swedish Defense Research Agency.
"It is very unstable, very sensitive to both friction and shocks," he said, adding the substance has no civilian use.
The same type of explosive was used by the four suicide bombers who killed 52 subway and bus passengers in London on July 7, 2005.
Police spokesman Sven-Erik Karlsson said police set up a security perimeter with a 1,000-foot (300-meter) radius around the Oskarshamn plant, but workers already inside were not evacuated.
Sweden's police intelligence agency, SAPO, was not involved in the investigation but "we are keeping ourselves informed," SAPO spokesman Jakob Larsson said.
The plant's three nuclear reactors account for about 10 percent of the electricity produced in Sweden. Operator OKG is jointly owned by E.ON of Germany and Finland's Fortum.
Officials said there were no signs that Wednesday's incident was linked to an act of vandalism in April when half a dozen fire extinguishers were sabotaged at the plant. That incident was still being investigated internally and had not been reported to police, plant spokeswoman Emelie Johannesson said.