(Bloomberg) -- China has completed what it says was “de-radicalization” training in its western Xinjiang region, officials said in Beijing, as the government sought to defend the widespread detention of ethnic minorities.

Top officials for the predominately Muslim region of Xinjiang made the claim Monday during a briefing to promote policies they said were responsible for ending a spate of terrorist attacks. The briefing came less than a week after the U.S. House of Representatives passed legislation that would sanction Chinese officials over percieved human rights abuses in the region, including what the United Nations says is the detention of as many as 1 million mostly Uighur Muslims.

“All the students in the centers studying the national common language, law, vocational skills and de-radicalization courses have all graduated,” said Shohrat Zakir, Xinjiang’s governor and No. 2 official. While that’s further than Zakir went in a similar briefing in July when he said “the majority” of people had returned to their homes, he provided no numbers or other supporting evidence. He didn’t say whether the “graduates” had been released.

It wasn’t immediately possible to verify the government’s claims, which have been previously questioned by activists. Independent analysis of satellite imagery, procurement records and government hiring announcements, as well as reporting by foreign media outlets including Bloomberg News, show that China has build a network of prison-like facilities across the region to house large populations.

The House action last week came after a pair of high-profile leaks of internal Communist Party documents illustrating a broad campaign to implement and conceal the detention program. China has denounced the U.S. legislation as an inappropriate attempt to interfere in what it argues is a reasonable effort to fight terrorism and religious extremism.

The bill “seriously violates international law and the basic principles of international relations and is a gross interference in China’s internal affairs,” Zakir told reporters Monday.

More on who the Uighurs are and why China is locking them up

The region of Xinjiang -- a remote area the size of Alaska where China’s anti-terrorism efforts have focused -- is home to about 10 million members of the Turkic-speaking Uighur ethnic group. Chinese President Xi Jinping launched a crackdown on the region after a series of deadly terrorist attacks in 2013.

Zakir, himself an ethnic Uighur, was one of four senior Xinjiang officials who defended the region’s policies Monday. He dismissed claims that 1 or 2 million people had been held in the detention centers as “groundless fabrications,” without providing numbers of his own.

--With assistance from Dandan Li.

To contact Bloomberg News staff for this story: James Mayger in Beijing at jmayger@bloomberg.net

To contact the editors responsible for this story: Brendan Scott at bscott66@bloomberg.net, Iain Marlow

©2019 Bloomberg L.P.