(CNN) - A prominent Chinese pastor and legal scholar is one of 100 Christians detained by authorities after he was reportedly arrested on allegations of "inciting subversion of state power."
Wang Yi and his wife, Jiang Rong, were taken into police custody early last week in the city of Chengdu, where they run the Early Rain Covenant Church, according to ChinaAid, a US-based nonprofit that advocates on behalf of China's Christian communities.
A church parishioner, who spoke on condition of anonymity, confirmed Wang's arrest in a phone call with CNN.
Authorities with China's National Religion Bureau did not respond to a request from CNN seeking comment.
Western governments and civil rights advocates outside China have condemned the mass arrest of the Early Rain parish as the latest move in Beijing's stepped up crackdown on independent religious practice.
China has been accused of carrying out a systematic campaign of human rights violations against hundreds of thousands of Muslim Uyghurs in the far western region of Xinjiang. China says its actions there are meant at combating violent extremism, and it has repeatedly denied claims that the region has turned into an Orwellian surveillance state.
Sam Brownback, the US ambassador at large for international religious freedom, cited the actions against the Early Rain Church and the reports from Xinjiang when announcing that China was one of ten countries designated a "country of concern" when it comes to religious freedom Tuesday.
"My particular concern now for China is they've increased these actions of persecution against faith community," Brownback said.
"China isn't backing away from the religious persecution; it seems to be expanding."
China is officially an atheist state, but religious practice is legal in the country -- albeit under the central government and Chinese Communist Party's rules and surveillance.
But some of the country's faithful attend underground or unregistered houses of worship to practice their religion freely.
Police have accused Early Rain of operating without registering with authorities, and Human Rights Watch says Wang and members of his church have been the subject of frequent harassment in recent years.
"Everyone who supports religious freedom should stand with Wang Yi and speak out against the Chinese government's repression of religion," said Yaqiu Wang, a China researcher at Human Rights Watch.
Rights advocates say the crackdown against underground churches and religious practice that's not state-sanctioned is less about religious practice itself and more about the Chinese Communist Party making sure it remains firmly in control of civil society.
"Under President Xi, the government has further tightened control over Christianity in its broad efforts to 'Sinicize' religion or 'adopt Chinese characteristics' -- in other words, to ensure that religious groups support the government and the Communist Party," Human Rights Watch said.
"The shutdown of a Protestant church in Chengdu epitomizes the Xi Jinping government's relentless assault on religious freedom in China," said Human Rights Watch's Wang.
"It makes a mockery of the government's claim that it respects religious beliefs."
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