Around two dozen supporters of a prominent Chinese human rights lawyer and three activists charged with subversion protested outside a northern city court amid widespread concerns that authorities were holding their trials in secret.

Flanked by Western diplomats, the supporters gathered outside the Tianjin No. 2 Intermediate People's Court on Monday calling for information to be disclosed about the four, whose mid-July indictments were the latest move by authorities waging a massive crackdown on legal activism over the past year.

Supporters included the wife of Gou Hongguo, one of the activists who was indicted with subversion and thought to be standing trial Monday, together with Zhou Shifeng, the head of a law firm at the center of the crackdown.

Court officials reached by phone said they had no information.