A former Iranian president Mohammad Khatami has denounced the trial of around 100 people accused of rioting after the re-election of President Mahmoud Ahmadinejad.
He says it is against the constitution, regular laws and rights of the citizens.
Mr Khatami said the court had relied on invalid confessions and the trial procedure was not being held in open session.
The 100 people have been charged with rioting, vandalism, having ties with counter-revolutionary groups and of planning to launch a "velvet revolution".
Around 2,000 protesters, reformists, political activists and journalists were initially detained by authorities in a crackdown to quell unrest after massive public protests over the 12 June vote.