SEOUL, South Korea — North Korea has detained another American citizen on charges of committing “hostile acts” against the country, the North’s official news agency reported on Sunday.

The man, identified as Kim Hak-song, was arrested on Saturday and was under investigation by the country’s related government agencies, the state-run Korean Central News Agency, or K.C.N.A., said.

It said that Mr. Kim worked at Pyongyang University of Science and Technology, a privately funded institution in the capital that was opened in 2010 with donations from Evangelical Christian movements outside the country.

K.C.N.A. provided no further detail about Mr. Kim or the circumstance of his detention.

The detention would raise to four the number of Americans known to be held in the secretive North.