North Korea detained a professor who is US citizen; at least 3rd American held At least two other U.S. citizens are believed held in North Korea.

 -- A U.S. citizen and academic was detained in North Korea while trying to leave the country with his wife on Saturday, a spokesperson for the university that employed him has confirmed.

Tony Kim, 58, who goes by jos Korean name Kim Sang-duk, was detained while trying to board a flight to China from Pyongyang's international airport, according to Colin McCulloch, director of external relations at Pyongyang University of Science and Technology (PUST), where Kim taught accounting.

The university's executive leadership released a statement Sunday saying that it "has learned that Mr Sang Duk (Tony) Kim was detained" by North Korean authorities as he was about to leave the country, "after several weeks of service, teaching at PUST.

"We understand that this detention is related to an investigation into matters that are not connected in any way with the work of PUST."

The Swedish Embassy in Pyongyang, which helps in handling U.S. affairs in North Korea, with which the United States does not have diplomatic relations, said that it was aware of a Korean American citizen being detained recently.

South Korean media said that Kim had done aid and relief work in North Korea.

At least two other American citizens are currently being held by North Korea -- Otto Warmbier, a a 21-year-old student at University of Virginia, and Kim Dong Chul.

The Associated Press contributed to this report.