North Korea is secretly moving political prisoners out of its most notorious concentration camp in Yodok, in apparent preparation for a PR exercise showing that conditions are not as bad as reported, a source claimed.

"The regime is transferring the inmates one by one during the night so that their movement can't be detected by satellites," the source said Monday.

The regime aims to show the camp to foreigners looking like little more than a collective farm, the source added. "The regime will probably send farmers to the political prison camp to do the labor there," the source said.

North Korea has recently admitted the existence of "reform through labor" camps in response to a damning UN human rights report.

The inmates of the Yodok camp are being moved to several other prison camps, the source added. Between 35,000 and 50,000 political prisoners have been held at Yodok, in remote North Hamgyong Province, at different times.

