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May 7, 2017, 1:00 PM UTC / Updated May 8, 2017, 2:53 AM UTC

SEOUL, South Korea — Another U.S. citizen has been detained in North Korea, officials said Sunday.

Kim Hak Song, who was working at Pyongyang Science and Technology University, was held for "hostile acts against the republic," the state-run news service KCNA said.

Pyongyang University of Science and Technology, where Kim had been working, confirmed that he was detained Saturday as he was preparing to leave the country. It said Kim was doing agricultural development work not connected with the university.

Kim is the fourth U.S.citizen to be held by the isolated country amid diplomatic tensions.

A third U.S. citizen, Kim Sang Dok, was detained in late April on similar grounds.