Christians in Hong Kong are coming to church dressed all in black as a protest against mainland China's crackdown on prominent congregations.

Church leaders at the Early Rain Covenant Church in Chengdu including its pastor Wang Yi are the latest to have been arrested by the authorities, who are particularly targeting 'underground' churches which are not part of official bodies.

According to the South China Morning Post, the movement has been started by five progressive Christian groups that have launched an internet campaign in support of the action. Organisers said they had reached 47,000 people via Facebook. The Post visited one church in Tai Po where a third of the 500-strong congregation was dressed in black. Next week numbers are expected to rise.

Hong Kong, formerly a British colony, experiences greater freedom than mainland China and Christians are more able to voice dissent.

According to a prayer letter from Early Rain Covenant Church reported by China Aid, some of those still in custody have been denied access to their lawyers.

Around 160 people from the church have now been arrested, some of whom have now been released but some of whom face criminal charges.

According to China Aid, preventing prisoners meeting with lawyers is 'a tactic that violates Chinese law but is often employed during procedures targeting prisoners incarcerated for political or religious reasons'.