A Korean-American was detained in North Korea amid heightened tensions in the region, sources told the Yonhap news agency in South Korea.
The U.S. citizen, who is reportedly a former professor at China's Yanbian University of Science and Technology and is in his late 50s, is only identified by his surname, Kim.
Sources told Yonhap that Kim was arrested at Pyongyang International Airport last week as he was trying to leave the country.
He had been involved in aid and relief programs to North Korea, the unidentified sources added.
"We have been informed and can confirm that there has been a detention of a U.S. citizen Saturday morning," Martina Aberg, deputy head of mission for the Swedish Embassy in North Korea, told CNN.
"He was prevented from getting on the flight out of Pyongyang,” she added. “We don't comment further than this."
The director of the World North Korea Research Center in Seoul, Ahn Chan-il , told Yonhap that that the North "seems to be intending to use Professor Kim as leverage in negotiations.”
South Korea went on heightened alert Friday while Russian officials pushed against reports that Moscow is moving troops to its border with the reclusive country.
South Korean officials are expected to meet with representatives from the U.S. and Japan this week to "discuss plans to rein in North Korea's additional high-strength provocations, to maximize pressure on the North, and to ensure China's constructive role in resolving the North Korea nuclear issue," the foreign ministry in Seoul said.
U.S. and Japanese military forces are currently holding joint exercises in the Philippine Sea.
Two other American citizens, Otto Warmbier and Kim Dong-chul, were sentenced to prison for what North Korea described as subversive acts. Warmbier is a University of Virginia student and Kim is a Korean-American pastor.
--This report was updated at 7:52 a.m.
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