PYONGYANG, North Korea - North Korea says an American citizen sentenced to 15 years hard labour has started life at a "special prison."

No other details were immediately available Wednesday about Kenneth Bae. Pyongyang said earlier this week that Bae informed his family on Friday that he couldn't appeal his April 30 sentence and that he asked his family to urge Washington to push for his amnesty.

Washington has called for Bae's release.

North Korea accuses Bae of trying to establish an anti-Pyongyang base in the North. There has been no statement from Bae.

Pyongyang denies speculation by outside analysts that it is using Bae to win diplomatic concessions.

Several other detained Americans have been released in recent years after prominent Americans travelled to Pyongyang.