A semiofficial Iranian news agency says a former government spokesman who became an opposition supporter has been sentenced to six years in prison.

Abdollah Ramazanzadeh was charged with fomenting unrest in order to topple the Iranian ruling system.

His trial was part of mass proceedings under way against more than 100 leading moderates, opposition figures and supporters who have challenged President Mahmoud Ahmadinejad's disputed re-election in June.

The Fars news agency reported on Thursday that Ramazanzadeh was found guilty of "acts against national security, propagating against the Islamic establishment and keeping classified documents."

Ramazanzadeh served until 2004 as spokesman under reformist President Mohammad Khatami.