China Aid Association said at least four of the leaders were still in police custody a week after their arrest.
Police have reportedly fined the church leaders and confiscated their money, mobile phones and books.
Two South Korean pastors were also arrested alongside the Chinese church leaders. CAA said they were expelled from China on Saturday for “engaging in illegal religious activities”.
China is officially atheist and Christians may only legally worship in state-sanctioned churches. However, tens of millions of Christians worship within a wide network of illegal churches, arguing that only God should be the head of the church and not the government.
Christian groups working with the persecuted church say house church members continue to face arrests, imprisonment and fines for their faith.
A CAA report published earlier in the month claimed that the persecution of house church Christians in Beijing rose 418 per cent in 2008, an increase it said was directly connected to last year’s Olympic Games.
The government has in recent years pledged to uphold religious freedom and the officially recognised Three-Self Patriotic Movement and China Christian Council recently announced plans to start distributing Bibles among the house churches.
House churches have often spoken of widespread Bible shortages among their members, due in large part to the tight control over Bible sales in China. China does not import Bibles and only registered churches – not general bookstores - are allowed to sell them.
Despite regular reports of arrests and imprisonment, persecution watchdog Open Doors says China has made progress. The group dropped China from its top 10 list of the world’s worst persecutors of Christians. It now ranks No 12 on the Open Doors World Watch List, down from No 10 in the previous year.