A young French academic and local employees of the British and French embassies appeared before an Iranian judge Saturday along with dozens of opposition figures accused of involvement in the country's postelection unrest.

The extraordinary mass trial in Tehran's Revolutionary Court demonstrates the government's resolve to discredit Iran's pro-reform movement as a tool of foreign countries — particularly Britain and the United States — trying to spark a revolution to topple Iran's Islamic system.

The appearance of the British Embassy employee appeared to catch Britain off guard, and the Foreign Office in London promised a response to what it called "this latest outrage."

The defendants stand accused of crimes including rioting, spying and plotting a "soft overthrow" of the regime after the disputed June 12 presidential election.

Iran's opposition and the hundreds of thousands who took to the streets after the election denounced official results that declared President Mahmoud Ahmadinejad the winner. The government has been eager to show that the outpouring was not the result of internal unrest but foreign interference.

During the session, a prosecutor read out an indictment saying the U.S. and Britain had plans to foment the unrest with the aim of toppling Iran's Islamic rulers through a "soft overthrow," the state-run Islamic Republic News Agency reported.

The vague indictment also accused the two powers of providing financial assistance to Iran's reformists to undermine hard-line clerics within the ruling system.

A reformist Web site said riot police attacked family members of the defendants and others gathered in front of the court to denounce the trial.

Saturday's hearing was the second in a trial that started a week ago, although it was a new group of defendants facing the judge. Human rights groups and Iran's opposition have criticized the trial as a sham and said televised confessions from defendants were scripted by authorities and extracted through pressure.

During Saturday's session, Hossein Rassam, a political analyst at the British Embassy arrested shortly after the start of the unrest, told the court that Britain was involved in fomenting the unrest, according the IRNA news agency.

He said a budget of 300,000 pounds — or about $500,000 — had been allocated to establish contacts with Iranian political groups, influential individuals and activists, IRNA reported.

The news agency quoted him as saying that he personally established contacts before the election with the campaign headquarters of Mir Hossein Mousavi, the pro-reform candidate who says he was robbed of victory.

"My main responsibility was to gather information from Tehran and other cities by setting up contacts with individuals and influential parties and political groups and to send reports to London. ... The British Embassy, due to its hostile policies in Iran and fear of exposure of its contacts inside Iran, employed local staff to establish such contacts. I established such contacts based on orders from embassy officials," IRNA quoted Rassam as saying.

Rassam has been charged with espionage and "acting against national security," IRNA reported.

In London, Britain's Foreign Office called his appeared unacceptable and said it contradicted assurances it had been given by senior Iranian officials.

"We deplore these trials and the so-called confessions of prisoners who have been denied their basic human rights," a Foreign Office statement said.

Britain's ambassador to Tehran was seeking clarification from Iranian authorities. "We will then decide on how to respond to this latest outrage," the statement said.

Eight other British Embassy staffers arrested along with Rassam were released after about a week in custody.

Among those seated in the front row at Saturday's hearing was a 23-year old French academic, Clotilde Reiss, who was reportedly arrested July 1 at Tehran airport. She wore a scarf over her hair and sat beside a police officer.

According to IRNA, she told the court that she made a mistake by attending a demonstration.

"I had personal motives to join gatherings to see what was happening out of curiosity but I admit that I made a mistake and should not have attended," IRNA quoted her as saying.

Reiss has been charged with acting against national security by joining protests, gathering information, taking photos and sending them abroad. France has called the charges baseless and senior European Union diplomats have demanded her release.

Nazak Afshar, a local employee of the French Embassy in Tehran, also told the court she was involved in postelection disturbances, IRNA reported. She has been charged with provoking unrest and being involved in riots.

"I damaged my record with what I did. Brothers at the Intelligence Ministry made me understand my mistake. ... I physically attended gatherings," the news agency quoted Afshar as saying.

IRNA said Afshar wept as she spoke of the regret she felt for her actions.

Iranian defendants appearing Saturday included Ali Tajernia, a former reformist lawmaker; Shahaboddin Tabatabaei, a prominent leader of the Islamic Iran Participation Front, Iran's largest reformist political party; and Ahmad Zeidabadi, an outspoken journalist opposing hard-liners.

TV images and pictures on state media showed rows of defendants in gray prison uniforms and others seated in a large, wood-paneled room decorated with pictures of Ayatollah Ruhollah Khomenei, the late Iranian revolutionary patriarch who came to power with the overthrow of the pro-Western Shah in 1979, and his successor, Ayatollah Ali Khamenei.

Iran's reformist and moderate parties have denounced the mass trial, describing it as a "ridiculous show."

Such a mass trial is unprecedented in Iran. Smaller-scale mass trials were held after the 1979 Iranian Revolution but usually in secret.