Four women have shaved their heads on the streets of Beijing to protest against the detention of a human rights lawyer without trial.

Wang Quanzhang has been in prison since 2015, and his wife, Li Wenzu, says she has travelled to the country's Supreme Court 31 times to try and lodge case documents, but has never been let inside.

Mr Wang, who is accused of undermining the government, was detained along with three others in a crackdown on lawyers.

No officials have been available to comment on the case.