After China abolished a notorious penal system based on forced labor in December 2013, the United States rewarded Beijing by removing the world's most populous country from a global blacklist of countries that are failing to combat modern-day slavery.

Shutting the detention camps had been a U.S. priority for more than a decade, according to a previously unreleased U.S. State Department memo seen by Reuters.

But two years after China announced it was ending the "re-education through labor" system, extrajudicial networks of detention facilities featuring torture and forced labor are thriving in its place, according to former detainees, their lawyers and people with knowledge of the facilities.