A foreign-funded university in the Democratic People's Republic of Korea (DPRK) has confirmed the arrest of a US citizen who was lecturing there – the third US national held in the country amid growing tensions between Pyongyang and Washington. 

Kim Sang-duk, or Tony Kim, was arrested at the capital's airport Saturday as he was about to leave after teaching at the Pyongyang University of Science and Technology (PUST) for several weeks, the school said.

The school, founded by evangelical Christians from overseas and opened in 2010, is known to have a number of US faculty members. Students are generally the children of the country's upper class families.

The reason for Kim's arrest was unclear, but was "not connected in any way with the work of PUST," the school said in a statement.   

"We cannot comment on anything that Mr. Kim may be alleged to have done that is not related to his teaching work and not on the PUST campus," it said. 

The Swedish embassy in Pyongyang, which handles issues involving US citizens as Washington has no diplomatic ties with the DPRK, is "actively involved" in talks, the school's external director, Colin McCulloch, said in a statement without elaborating. 

The Swedish embassy and the South Korean government declined to comment on the matter. 

Kim is a former professor at the Yanbian University of Science and Technology in China, close to the DPRK border. Its website lists his speciality as accounting. 

The US State Department said it was aware of media reports over the case, but gave no official confirmation. 

South Korea's Yonhap news agency gave Kim's age as 55 and said he had been involved in relief activities for children in rural parts of the DPRK. It cited a source familiar with the matter who described Kim as a "religiously devoted man." "He has been involved in relief activities in the DPRK for so long... I don't understand why he was suddenly arrested," the source was quoted as saying.   

Two other US citizens, college student Otto Warmbier and Korean-American pastor Kim Dong-chul, are currently being held in the DPRK after being sentenced to long prison terms. The pastor was sentenced last year to 10 years of hard labor for spying. Warmbier was sentenced to 15 years in 2016 for stealing propaganda material and for "crimes against the state." 

The DPRK 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 or former US presidents. 

(Source: AFP)