Washington, Jan 28 (IANS): New commercial satellite imagery has indicated that operations at a plutonium production reactor located in North Korea's Yongbyon Nuclear Scientific Research Centre has likely resumed, according to a US think tank.

A statement issued on Friday by 38 North, that monitors nuclear activity in North Korea, said an analysis from January 18 showed that Pyongyang was preparing to restart the reactor, after unloading spent fuel rods for a re-processing campaign that produced additional plutonium for its nuclear weapons stockpile. 

"Imagery from January 22 showed a water plume (most probably warm) originating from the cooling water outlet of the reactor, an indication that the reactor is very likely operating," it said.

Without further data, it is impossible to estimate at what power level the reactor is running, although it could be considerable, the statement added.

The Yongbyon nuclear complex, which includes a 5-megawatt reactor and other facilities, was shut down under an agreement in 2007 involving North Korea and five other countries: the US, China, Japan, Russia and South Korea, the Voice of America reported. 

North Korea, however, broke the agreement in 2013 and said it was resuming activity at the site, 90 km north of the capital, Pyongyang.

The International Atomic Energy Agency said last year that the Yongbyon reactor had been restarted, either for enrichment or re-processing.