A Chinese state media report and a boat owner say unidentified North Koreans have taken one of his fishing boats and its crew and are demanding a ransom.

Yu Xuejun said on a verified microblog that his boat was in Chinese waters on May 5 when it was boarded and detained by gun-wielding North Koreans. He wrote on Tencent Weibo late Saturday that the "North Korean side" had demanded 600,000 yuan ($100,000).

Calls to the maritime police and foreign and public security ministries rang unanswered Sunday.

The respected Southern Metropolis Daily reported the case Sunday. It quoted an unidentified official from Liaoning maritime police as confirming the case had been reported to them. It said public security authorities had requested "the North Korean side" release the boat and 16 crew.