Beijing city authorities have banned one of the largest unofficial Protestant churches in the city and confiscated "illegal promotional materials," amid a deepening crackdown on China's "underground" churches.

The Zion church had for years operated with relative freedom, hosting hundreds of worshippers every weekend in an expansive, specially renovated hall in north Beijing.

But since April, after they rejected requests from authorities to install closed-circuit TV cameras in the building, the church has faced growing pressure from the authorities and has been threatened with eviction.