Satellite images taken between January and this month show a North Korean nuclear reactor that can yield material for atomic bombs may be operating again at low power or intermittently, U.S. experts said on Wednesday.

A report from David Albright and Serena Kelleher-Vergantini at Washington's Institute for Science and International Security said the imagery also suggested that a centrifuge plant at the Yongbyon nuclear complex had been operated and that North Korea may be preparing to conduct renovations at this plant.

The think tank said last year that satellite imagery from late August and late September indicated the Yongbyon reactor may have been partially or completely shut down.