China is coming under increased scrutiny for its internment camps for Uyghurs in the northwestern province of Xinjiang.

The Uyghurs are a Muslim ethnic minority in far western China, but Beijing has detained hundreds of thousands of innocent Uyghurs and subjected them to a program that the Communist Party says offers them an escape from poverty and prevents the spread of radical Islam.

Satellite imagery and and accounts from the region now show that detained Uyghurs are being put on production lines of factories built within internment camps. They essentially have no choice but to take the jobs and accept orders.

“These people who are detained provide free or low-cost forced labor for these factories,” said Mehmet Volkan Kasikci, a researcher in Turkey who has collected accounts of inmates in the factories by interviewing relatives who have left China.

The New York Times reports:

China has defied an international outcry against the vast internment program in Xinjiang, which holds Muslims and forces them to renounce religious piety and pledge loyalty to the party. The emerging labor program underlines the government’s determination to continue operating the camps despite calls from United Nations human rights officials, the United States and other governments to close them. The program aims to transform scattered Uighurs, Kazakhs and other ethnic minorities — many of them farmers, shopkeepers and tradespeople — into a disciplined, Chinese-speaking industrial work force, loyal to the Communist Party and factory bosses, according to official plans published online. Serikzhan Bilash, a founder of Atajurt Kazakh Human Rights, an organization in Kazakhstan that helps ethnic Kazakhs who have left neighboring Xinjiang, said he had interviewed relatives of 10 inmates who had told their families that they were made to work in factories after undergoing indoctrination in the camps. They mostly made clothes, and they called their employers “black factories,” because of the low wages and tough conditions, he said.

The growing problem of forced labor in Uyghur internment camps should also send warning signs to companies importing goods from Xinjiang.

Hetian Taida, a company in Xinjiang that was shown on a prime-time state television broadcast promoting the camps, recently sent a container of T-shirts to Badger Sportswear, a company based in North Carolina. Still, it was unclear if the Hetian Taida factory shown on TV was within a detention camp or if the specific T-shirts sent to Badger Sportswear were produced by Uyghur inmates.

Ginny Gasswint, an executive at Badger Sportswear, said the company ordered a small amount of products from Xinjiang, and used Worldwide Responsible Accredited Production, a nonprofit certification organization, to ensure that its suppliers meet standards.

Seth Lennon, a spokesman for Worldwide, said that Hetian Taida had only recently enrolled in its program, but stressed that “We will certainly look into this.”