North Korea has righted a naval ship that capsized and was damaged during a botched launch in May, restoring its balance and mooring it to a pier, state media confirmed.

North Korea says it righted a capsized destroyer and moored it at a pier in the northeastern port of Chongjin as it continues to repair a new warship leader Kim Jong Un has described as a significant asset for his nuclear-armed military.

North Korea righted a capsized 5,000-ton warship and moored it at a pier in the Chongjin Shipyard state-run media reported, two weeks after a failed launch that leader Kim Jong Un condemned as a "criminal act.