The Chinese Communist Party promotes atheism and tightly controls religion - still, some Christian groups are calling this the most extensive crackdown against the faith in decades. Christians have long been pressured to join only state-sanctioned churches that are led by government-approved pastors and toe the party line. It is unclear if the detainees have been formally charged.
"Such systematic persecution is not only an affront to the Church of God but also a public challenge to the international community," Zion Church said in a statement.
Urging China to release the church leaders, US Secretary of State Marco Rubio said in a statement on Sunday that "this crackdown further demonstrates how the CCP exercises hostility towards Christians who reject Party interference in their faith and choose to worship at unregistered house churches".
