BEIJING - Western forces are trying to use Christianity to influence China's society and even "subvert" the government, a senior official said, warning that Chinese Christians needed to follow a Chinese model of the religion.

China's constitution guarantees religious freedom, but since President Xi Jinping took office six years ago, the government has tightened restrictions on religions seen as a challenge to the authority of the ruling Communist Party.

The government has cracked down on underground churches, both Protestant and Catholic, even as it seeks to improve relations with the Vatican.

In a speech on Monday, Xu Xiaohong head of the National Committee of the Three-Self Patriotic Movement of the Protestant Churches in China, said there were many problems with Christianity in the country, including "infiltration" from abroad and "private meeting places".

"It must be recognised that our movement's surname is 'China' and not 'Western'," Xu said, according to remarks reported on Tuesday by the United Front Work Department, which is in charge of co-opting non-communists, ethnic minorities and religious groups.

"Anti-China forces in the West are trying to continue to influence China's social stability and even subvert our country's political power through Christianity, and it is doomed to fail," he said, speaking to parliament's largely ceremonial advisory body.

"For individual black sheep who, under the banner of Christianity, participate in subverting national security, we firmly support the country to bring them to justice."

Only by eliminating the "stigma of foreign religion" in China's Christianity can its believers benefit society, he added.

"Only by continually drawing on the fine traditions of Chinese culture, can China's Christianity be rooted in the fertile soil of Chinese culture and become a religion recognised by the Chinese themselves," Xu added.

"Only by continuously carrying forward and practicing the core values ​​of socialism can our Christianity truly be suited to socialist society."

China has been following a policy it calls the "Sinicisation" of religion, trying to root out foreign influences and enforce obedience to the Communist Party.

Restrictions on religion have attracted particular concern in the United States. Last week, during a visit to Hong Kong, the US ambassador for religious freedom called on Beijing to end religious persecution.

What China calls a de-radicalisation programme in its restive far western region of Xinjiang has also caused widespread opprobrium in Western capitals and amongst rights groups, who say authorities have been placing Muslims there in internment camps.

The government says they are vocational training centres where the Uighur people who call Xinjiang home and other Muslim peoples are sent to learn about the law and the Mandarin language, and has defended the practice.

Yang Jie, an imam from Xinjiang, told the same advisory body on Monday that some adherents had poor "religious and civic awareness", which made them vulnerable to "the temptation and incitement of religious extremist forces".

They mistakenly believed that their religion came before their citizenship, and that certain illegal acts were a "firm expression of faith", Yang said.

"This wrong view and behaviour has seriously affected social stability, ethnic unity and religious harmony, and has vilified the social image of the Muslim community and must be resolutely stopped."