Stockholm - Two of Sweden's 10 nuclear reactors that have been offline since October were Tuesday granted permission to restart operations, the nuclear watchdog said.

The reactors were taken offline after cracks were detected in some control rods. Faulty rods have now been replaced.

The Swedish Radiation Safety Authority said the two plants were to be allowed to go back online until scheduled maintenance work next year.

The agency said it would closely monitor efforts by the operators to determine the cause of the cracks in the control rods used to control the nuclear fission process.

The nuclear watchdog's decision applies for one reactor at Forsmark, north of Stockholm and one reactor at the Oskarshamn plant, south-eastern Sweden.

Maintenance work was due end of March at reactor 3 at Oskarshamn and end of July on Forsmark 3, the agency said.

The Oskarshamn plant is operated by energy groups E. ON of Germany and Finland's Fortum, while Forsmark is majority-owned by state- controlled energy group Vattenfall.

Sweden operated 12 nuclear reactors at most. Two at the Barseback plant in southern Sweden have been decommissioned, the most recent in May 2005. (dpa)