North Korea has expelled an American citizen of Korean origin, accusing him ofspying for the South.

The North Korean news agency KCNA said the man, James Jin-kyong Kim, had admitted to conducting espionage activity for South Korea.

It added that he was being treated leniently in the interests of preserving good US-North Korean relations.

Mr Kim -- who runs an Engineering College in China -- has been held in North Korea since last month, when he travelled to Pyongyang on business.

He would not talk to journalists on his return to China.