University professor Tony Kim also known as Kim Sang-duk, who is a Korean-American citizen, has been detained on Saturday. This has increased the number of Americans believed to be held by the secretive nation to three.

If confirmed, the arrest would complicate the relations of both nations. Park Chan-mo, chancellor of Pyongyang University of Science and Technology (PUST) revealed that Kim was detained over the weekend.

He also said, according to the New York Times, that Kim had taught accounting at the university for nearly a month. Kim previously taught at Yanbian University of Science and Technology in China before he went to Pyongyang.

Apparently, Kim was detained by officials at Sunan International Airport in Pyongyang. This was when he was trying to leave North Korea.

A South Korean news agency described Kim as being in his late 50s. It was also revealed that he had been involved in aid and relief programs to North Korea.

The Swedish Embassy in the reclusive country said that it was aware that a Korean-American citizen was recently detained. The agency checks consular affairs in North Korea on behalf of the United States since the latter does not have formal diplomatic ties with the country.

The South Korean government, with its Unification Ministry and National Intelligence Service, was unable to confirm the report. However, the reclusive country has been known to detain foreigners in order to gain diplomatic leverage. It is believed that two other Americans are known to be held in the country.

PUST was founded about seven years ago by Korean-American businessman James Kim. It became the only private university in the country.

According to a 2014 report by BBC, students at the institution are hand-picked by the North Korean government to attend. Classes are taught in English but traditions of the country still remain.

Bustle noted that the two other Americans believed to be detained in the reclusive country are Otto Warmbier, a college student in his 20s, and Kim Dong Chul. Both of them have been sentenced to several years of hard labor last year.