North Korea has detained another US citizen for committing "hostile acts", it said yesterday, its second arrest of an American in a fortnight with tensions high between Pyongyang and Washington.

The arrest of Kim Hak-Song means that the North is holding four US citizens, with the two countries at loggerheads over Pyongyang's nuclear and missile ambitions.

Kim was detained on Saturday, KCNA reported.

It said Kim had been working for the Pyongyang University of Science and Technology (PUST) which is known to have a number of American faculty members.