North Korea's main nuclear reactor recently re-started operations after suspending them for about two weeks due to a technical problem, a news report said on Monday.
The communist state halted work at its only operating reactor, in Yongbyon, for 10-15 days last month but reactivated it recently, Yonhap news agency reported, citing an unidentified intelligence official.
"It's believed that the reactor was halted for a technical problem," the official was quoted as saying. "It does not appear to be related to implementation of the February 13 agreement."
The official was referring to a deal in which the North pledged to close the reactor in exchange for economic aid and political concessions.
Pyongyang was supposed to shut down the facility by mid-April, but has not done so because of a separate banking dispute with the United States.
It was unclear what the technical problem was.
Earlier in the day, the Chosun Ilbo newspaper carried a similar report citing unidentified officials, but said the reactor had not been restarted yet.
The report said the reactor shutdown may be a ploy to make Washington believe the North is removing spent fuel rods from the reactor - a move necessary to reprocess them for plutonium, a key substance in making nuclear weapons.
But the intelligence official cited in the Yonhap report said the suspension of the reactor's operations was not believed to be aimed at removing spent fuel rods.