North Korea has detained a US citizen, bringing the total number of Americans held by the isolated country to three.
The man, a Korean-American in his 50s identified only by his surname Kim, had been in North Korea for a month to discuss aid and relief activities, the South Korean news agency Yonhap said.
He was reportedly arrested at Pyongyang International Airport on his way out of the country.
The Swedish Embassy in North Korea’s capital of Pyongyang said it was aware of a Korean-American citizen being detained recently, but could not comment further.
The embassy looks after consular affairs for the United States in North Korea because the two countries do not have diplomatic relations.
The man was a former professor at Yanbian University of Science and Technology (YUST), Yonhap said, citing unnamed sources.
YUST, a university in neighbouring China, has a sister university in Pyongyang.
South Korea’s Unification Ministry and its intelligence agency both said they were unable to confirm the report.
North Korea, which has been criticised for its human rights record, has in the past used detained Americans to extract high-profile visits from the United States.
North Korea was already holding two Americans.
Otto Warmbier, a 22-year-old student, was detained in January last year and sentenced to 15 years of hard labour by a North Korean court for attempting to steal a propaganda banner.
In March 2016, Korean-American Kim Dong Chul, 62, was sentenced to 10 years hard labour for subversion.
US missionary Kenneth Bae was arrested in 2012 and sentenced to 15 years hard labour for crimes against the state. He was released two years later.
Reuters and AP contributed to this report.