Some of Jiang’s supporters and about half a dozen foreign diplomats gathered outside the Changsha Intermediate People’s Court in Hunan province on Tuesday.

His supporters included the wives of other lawyers and activists caught up in the “709 crackdown” on civil rights campaigners on the mainland in July 2015.

The crowd was closely monitored by plainclothes policemen.

Roadblocks were also set up across the street by the courthouse.

Three other main roads in the area were also closed to traffic for “emergency construction”, according to a local radio station - a common practice for politically sensitive cases.

The hearing is being webcast on the court’s social media account, but with a delay.

Jiang’s wife, Jin Bianling, who fled China for the United States in 2013, said she had only learned about her husband’s trial through a news report and neither she nor Jiang’s family-appointed lawyers had been notified by the authorities.

Jiang, 46, took on politically sensitive cases until his legal licence was revoked in 2009, but he continued his rights activism.

He disappeared in November last year after travelling to Changsha to visit the rights lawyer Xie Yang, who was detained in the “709 crackdown”.

A month later the authorities confirmed they were holding Jiang.

State media released an interview with Jiang in March in which he said he helped fabricate accounts that Xie was tortured to curry favour with Western media. His wife and rights groups dismissed the appearance as a forced confession.

A slew of lawyers and activists have been jailed or given suspended sentences on subversion charges since last year.