SEOUL • North Korea has detained another US citizen, South Korea's Yonhap news agency reported yesterday, bringing the total number of Americans held by the isolated country to three.

Korean-American Tony Kim had spent a month teaching an accounting course at the Pyongyang University of Science and Technology (PUST), its chancellor Park Chan Mo told Reuters yesterday.

Mr Kim, who also goes by his Korean name Kim Sang Duk, was detained by North Korean officials at Pyongyang International Airport as he attempted to leave the country, Dr Park said.

"The cause of his arrest is not known but some officials at PUST told me his arrest was not related to his work at PUST. He had been involved with some other activities outside PUST such as helping an orphanage," Dr Park said.

South Korea's National Intelligence Service said it was not aware of the reported arrest. The director of a Seoul-based group called the World North Korea Research Centre said his sources in Pyongyang confirmed the arrest.

Mr Ahn Chan Il, a former defector, said: "It is important for them to hold a US citizen hostage at this point to prevent Washington from carrying out a decapitation of Kim Jong Un. It's also a resolve to point a double-action revolver against the US and China because he is a US citizen who worked in China."

North Korea has, in the past, used detained Americans to extract high-profile visits from the United States, with which it has no formal diplomatic relations.

Student Otto Warmbier, 22, was detained in January last year and sentenced to 15 years' hard labour for attempting to steal a propaganda banner. Two months later, Korean-American Kim Dong Chul, 62, was sentenced to 10 years' hard labour for subversion.

Pyongyang has arrested and jailed several US citizens in the past decade, often releasing them only after high-profile visits by current or former US officials.

REUTERS, AGENCE FRANCE-PRESSE