The International Atomic Energy Agency(IAEA) has detected signs that North Korea restarted its Yongbyon nuclear facility in the first quarter of this year. 

Japan's Kyodo news agency reported on Sunday that the UN nuclear watchdog stated in a recent report that it found multiple signs of resumed activity at the North's nuclear reprocessing facility.

It also noted that activities related to the movement of chemical tanks at the reprocessing plant or related equipment was seen, however, these activities stopped early last month.

The IAEA said movement was also detected in or around a uranium-enrichment facility where centrifuges may have been operating.

The North's Atomic Energy Institute told Kyodo news last week that it has resumed plutonium production by reprocessing spent fuel rods from a graphite-moderated reactor at its Yongbyon nuclear complex.