"This is truly a shameful decision," Dima Litvinov, head of the anti-nuclear campaign of the environmental group Greenpeace in Sweden, told Reuters.

After a four-year political struggle, the Swedish government decided it would give the Oskarshamn nuclear power plant limited permission to use MOX - mixed uranium and plutonium oxide fuel.

About 850 kilos (1,870 pounds) of plutonium in the MOX fuel was used by the Oskarshamn plant between 1975 and 1982 and then reprocessed in Britain.

The government said by allowing Oskarshamn to import the reprocessed fuel, Sweden was taking responsibility for handling atomic waste that it had generated.

But Greenpeace, which with other groups recently hampered shipping of MOX from Japan to England, said it was extremely dangerous to transport the material to Sweden.

Some critics fear the potentially weapons-grade MOX could be seized on the high seas by terrorists.

"We don't usually reveal details of action, but certainly we will not let this go on," Litvinov said. "I expect strong protests from Greenpeace and also from others."

In September, anti-nuclear campaigners including Greenpeace confronted two ships carrying MOX to Sellafield, a nuclear fuel reprocessing plant in England, from Japan.