Twenty prominent lawyers and jurists from Europe, Canada, the United States and Australia are urging Chinese President Xi Jinping to release a dozen Chinese lawyers and legal assistants held in detention.

In an open letter that appeared in the British newspaper The Guardian on Monday, the Western legal professionals expressed worries that the Chinese lawyers have been denied legal access since their July detention.

China has arrested six rights lawyers and legal assistants on suspicion of state subversion, and three more on suspicion of inciting state subversion. Others are yet to be charged, but their whereabouts unknown.

The lawyers have sought to use China's own laws to hold officials accountable or to protect citizens' rights, but Beijing says they are trying to sabotage the judicial system with improper activism.