..."I'm not so happy here. There is nobody who speaks my language. I'm so far from home," volunteered a tentative young woman in a T-shirt and sweatpants who said she was from Pyongyang, the North Korean capital.

But as she spoke, an older woman with stern posture and an expressionless face — a North Korean security official — passed by in the corridor. The young women scattered wordlessly and disappeared into another room, closing and bolting the door behind them.

Hundreds of young North Korean women are working in garment and leather factories like this one, easing a labor shortage in small Czech towns. Their presence in this new member of the European Union is an echo of North Korea's former alliance with other Communist countries.

The North Korean government keeps most of the earnings, apparently one of the few legal sources of hard currency for an isolated and impoverished regime living off counterfeiting, drug trading and weapons sales.

Experts estimate 10,000 to 15,000 North Koreans are working abroad on behalf of their government in jobs ranging from nursing to construction work. North Korea has sent workers to Russia, Libya, Bulgaria, Saudi Arabia and Angola, in addition to the Czech Republic, defectors say...