A prosecutor has demanded "maximum punishment" for a senior reformer accused of acting against national security, a crime which can carry the death sentence, in Iran's fourth mass trial of moderates since a disputed election.

Saeed Hajjarian, disabled since an assassination attempt in 2000, was among several prominent opposition figures in the dock charged with fomenting huge street protests that followed the June presidential election.

The poll plunged Iran into its most serious internal crisis since the 1979 Islamic revolution, exposing deep divisions in its ruling elite and further straining ties with the West.

"The prosecutor ... called for maximum punishment for Hajjarian considering the importance of the case," the official IRNA news agency reported.

Analysts regard the trials as an attempt by the authorities to uproot the moderate opposition and put an end to protests that erupted after the election, which defeated candidates say was rigged in favour of hardline President Mahmoud Ahmadinejad.

Several of the accused are members of Iran's leading reformist party, Mosharekat, whose website denounced the latest Revolutionary Court session as another show trial forming part of what it called an "ugly scenario".

It said some 200 relatives of those on trial gathered outside the court and that police failed to disperse them.

The state broadcaster said Iranian-American scholar Kian Tajbakhsh was also accused of acting against national security and of espionage, charges likely to anger Washington.

Those on trial also included former Deputy Interior Minister Mostafa Tajzadeh and business newspaper editor Saeed Laylaz, an outspoken critic of Ahmadinejad's economic policies.

Some, such as former Deputy Foreign Minister Mohsen Aminzadeh and former government spokesman Abdollah Ramezanzadeh, had appeared at an earlier trial session.

Detained about two months ago, several of them appeared to have lost weight during their time in jail and looked pale.

"Plotters"    

IRNA said the accused were "the plotters of recent riots and disturbances" after the election, which officials have portrayed as a foreign-backed bid to topple the clerical leadership.

State television showed Hajjarian -- a former deputy intelligence minister turned architect of the reform movement -- and fellow accused sitting in rows in the courtroom in prison clothes as they listened to a prosecutor reading the charges.

"Hajjarian is charged with acting against national security and propaganda against the Islamic establishment by spreading suspicion of vote-rigging ... and provoking illegal protests," IRNA quoted the indictment as saying.

In a statement read out in court by an associate, Hajjarian said he had "made major mistakes during the election by presenting incorrect analyses ... and I apologise to the Iranian nation for those mistakes," Fars News Agency reported.

Most of the accused former officials held their positions during the 1997-2005 presidency of Mohammad Khatami, who backed moderate opposition leader Mirhossein Mousavi in the election.

While many of their allies have been put on trial, the authorities have not yet arrested Mousavi or pro-reform cleric Mehdi Karoubi despite repeated calls from hardliners.

Karoubi, who came fourth in the election, has also angered his foes by saying some imprisoned protesters were raped and abused in jail, a charge government officials have rejected.

Western countries and human rights groups have condemned the trials. After the first session on August 1, Mousavi said confessions by some of the accused were made under duress.

Iran has held three mass trials already this month of more than 100 detainees, including a former vice president and other senior politicians.

A French teaching assistant and two Iranians working for the Britis