An outspoken Chinese pastor and his wife face up to 15 years in prison after being charged with inciting to subvert state power, a sign that Chinese authorities are intensifying a crackdown on religious groups, one of the most serious in recent decades.

Wang Yi, 45, who runs the independent Early Rain Covenant Church in the southwestern city of Chengdu, was detained last weekend along with over 100 members of his congregation.

As of Thursday, most of the group’s main leaders were still in custody and the police had sealed off the church, which occupies the floor of an office building.

The move against the church comes as the authorities have gradually constricted religious rights and sought to eliminate independent places of worship.