Here, Uighur men gather for a holiday meal in Turpan County, Xinjiang, in 2016.
China says its network of detention centres will also teach Mandarin Chinese, legal concepts and provide vocational training.
Rubio also said he would nominate a jailed Uighur scholar, Ilham Tohti, for the Nobel Peace Prize and urge the International Olympic Committee to review China's plans to host 2022 Winter Olympics.
Beijing has denied reports of the mass detention of its citizens in camps but evidence is mounting in the form of government documents and testimonies from former detainees.
China is undertaking unprecedented repression of its ethnic minorities including Muslim Uighurs, with authoritarian tactics potentially constituting "crimes against humanity" as human rights conditions deteriorate, a damning USA congressional report released Wednesday concluded.
The amended legislation states that Chinese regional governments "can set up vocational education and training centers.to educate and transform those who have been influenced by extremism".
Beijing has been routinely criticized for what many describe as a crackdown against religion in the country.
Xinjiang is officially designated as an autonomous region within China, like Tibet to its south.
More than one million Muslims are reportedly being held in the Xinjiang region in the west of the country in internment camps.
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The secretive inmate transfers began earlier this year, according to a Radio Free Asia report, but reports of Beijing requisitioning the Xinjiang train station has observers concerned the operation is ramping up.
FILE - In this November 4, 2017 file photo, Uighur security personnel patrol near the Id Kah Mosque in Kashgar in western China´s Xinjiang region.
US lawmakers on Wednesday called for a stronger response to the Chinese government's repression of Muslims in China's far west and asked the FBI to investigate claims of intimidation against some immigrant communities in the United States.
"Without due process, Xinjiang's political education centers remain arbitrary and abusive, and no tweaks in national or regional rules can change that".
Former Xinjiang detainee Omir Bekali demonstrates how he was strung up by his arms in Chinese detention before being sent to another internment camp during an interview in Almaty, Kazakhstan, in March 2018.
The other 4.5 million Catholics comprise what is often referred to as the "underground" Catholic Church in China, who are dubious of party-sanctioned and elected bishops and their teachings "because they believe legitimate ecclesiastical authority can be conferred only by the Pope's mandate, and they also object to affiliation with the patriotic religious association for Chinese Catholics, the Catholic Patriotic Association (CPA)".
"If you do not say it's the best way, maybe it's the necessary way to deal with Islamic or religious extremism", Li said, according to Reuters.
Many Chinese Catholics and religious-freedom experts have expressed doubts about whether the deal will actually bring unity, or whether it will further encourage the party's control over the Church in China and further divide Chinese Catholics.