On Monday, White House press secretary Sean Spicer admitted news that a fourth US citizen had been detained by the hermit state was “concerning”.
He told reporters: “We’re well aware of it and we’re going to work through the embassy of Sweden through our State Department, to seek the release of the individuals there.”
Both the US and the UK do not have diplomatic relations with North Korea, so any negotiations are done through the Swedish embassy in Pyongyang.
Kim Hak-song, who works for the Pyongyang’s University of Science and Technology, became the fourth American citizen to be held by the hermit state.
North Korea’s official KCNA news agency released a statement announcing the latest arrest.
It said: “A relevant institution of the Democratic People’s Republic of Korea detained American citizen Kim Hak-song on May 6 under a law of the DPRK on suspension of his hostile acts against it.”
On April 21, US-Korean citizen Kim Sang-duk was arrested at Pyongyang International Airport after spending around a month in North Korea taking part in humanitarian activities.
The other two US citizens already held in North Korea are Otto Warmbier, a 22-year-old student and Kim Dong Chul, a 62-year-old Korean-American missionary.
Mr Warmbier was detained in January 2016 and sentenced to 15 years hard labour for attempting to steal a propaganda banner.
Two months later, Kim Dong Chul was sentenced to 10 years hard labour for subversion. Neither has appeared in public since their sentencing.
The news comes amid heightened tensions between North Korea and the international community, with the US, China and a host of European countries working together to find a resolution to ongoing hostilities.
Meanwhile, South Koreans are set to go to the polls today to elect a new president after a corruption scandal brought down former leader Park Geun-hye.
The frontrunner, Moon Jae-in, favours more negotiations with North Korea and says he wold be willing to visit Pyongyang to defuse tensions.
His main challengers are IT tycoon Ahn Cheol-Soo, who supports a strong military build-up to fend off any aggression from their neighbours in the North, and Hong Joon-Pyo, who has been dubbed ‘Korea’s Trump’ for his outspoken rhetoric and sexist remarks.