A Chinese Protestant pastor is vowing to keep preaching to his flock despite the closure of his prominent underground church in Beijing, defying the government's intensifying pressure on religious groups.

Pastor Jin Mingri had given sermons at the Zion Church, one of the biggest unofficial congregations in the country, for the past decade until local officials shut it down on Sunday.

Its nine other satellite venues have also been closed, but Jin remains adamant that he will continue running the church.

“A church is more than just about a space,” he told AFP in an interview. “It's about gathering together to worship, it's about belief.”

Housed on the third storey of a nondescript commercial building in a northern Beijing suburb, Zion had up to 1,600 people attending its services each weekend.

But on September 9, some 70 officers stormed into Zion's premises and ordered everyone out, tearing down signs and the church's logo, Jin said.

The local civil affairs bureau said an investigation found that the church “was not registered and carried out activities in the name of social organisations without authorisation”.

The church's troubles started in February this year as tighter regulations on religious groups kicked in.

Authorities asked that the church install CCTV cameras in the sanctuary.

Jin refused.

“In the 70 year history of the people's republic, (Christians) have had a lot of harm and ill done to us, so churchgoers wouldn't feel too comfortable about their personal information being made public,” he said. “So we said no to the installation.”

It marked the start a sustained campaign, with church members threatened at home and at their workplaces, and some evicted by their landlords or asked to leave their jobs because of their links to Zion, Jin said.

He added that the authorities have branded his church a “cult”.

The building's owners were also pressured to prematurely end their partnership, refusing to renew the church's lease after it expired in August and plastering eviction notices outside.

Churchgoers were also handed similar notices whenever they left the building.

Since then, Jin estimates the church has lost up to 400 followers.

Jin said he is harassed daily by officers and was briefly detained after he tried to retrieve personal items from the shuttered church on Tuesday.

Dozens of officers guarded the compound housing the former church this week, preventing AFP journalists from entering the building.

“The way they are trying to control religion, they are using tactics from the former Soviet Union... where the church is a political tool,” he said.

"Burnt bibles"

China's top leaders have recently called for the “Sinicisation” of religious practice — bringing it in line with “traditional” Chinese values and culture — sparking concern among rights groups.

This week, draft regulations suggested Beijing is looking to restrict religious content online, such as images of people praying or chanting.

Christians in the country are split between unofficial “house” or “underground” churches like Zion, and state-sanctioned churches where Communist Party songs also feature in the order of service.

Churches in central Henan province have seen their crosses torn down, followers harassed and buildings shuttered, according to Bob Fu, founder of ChinaAid, a Christian human rights non-govermental organisation.

The closures of churches represent “a significant escalation on President Xi's crackdown against religious freedom in China,” Fu told AFP.

“Now that the Chinese Communist Party has started to burn Bibles and coerce millions of believers in the Christian faith and other religious minorities to even sign a written pledge to renounce their basic religious beliefs, the international community should be alarmed and outraged.”

"Social upheaval"

The state-linked China Christian Council estimates the country has around 20 million Christians — excluding Catholics — in official churches supervised by the authorities.

But the true number of worshippers could be higher, up to 70 million, according to some estimates.

China's roughly 12 million Catholics are also divided between a government-run association, whose clergy are chosen by the atheist Communist Party, and an unofficial underground church loyal to the Vatican.

Jin believes there will be “social upheaval” should the government try to erase religion, adding that he will continue to lead worship sessions outside the former church building.

“This is a new generation, which is why the church has to be alert, and be ready to accept this challenge,” he said. “We must continue to fight for the truth, and stand by our faith to respond to this challenge as it is our responsibility."