The trial in a $2.6 billion dollar banking fraud case that the Iranian media describe as the country's biggest ever opened on Saturday with some of the 32 accused facing possible death sentences.
The accused were charged with involvement in taking bribes and financial corruption, Iranian media reported.
The lead defendant, who was identified only by the initials MA, is accused of being "corrupt on earth," a charge which carries the death penalty under Iran's penal code, the reports said.
The fraud, as it surfaced last September, allegedly saw a private consortium amass trillions of rials through forged letters of credit approved by half a dozen Iranian banks.
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At the centre of the fraud is a company called the Aria group, which was founded in 2005 with a mere $50,000. In 2011, estimates put its value at more than $3.5 billion.
The scandal took a political turn after media opposed to President Mahmoud Ahmadinejad published a letter attributed to his chief of staff and principal advisor, Esfandiar Rahim Mashaie, reportedly asking Economy Minister Shamseddin Hosseini to facilitate the Aria group's operations.
On September 14, Ahmadinejad spoke in spirited defence of Mashaie and urged the judiciary to launch an "honest" probe into the case.
The fraud almost forced Hosseini from office but in November he survived an impeachment vote in parliament after being accused of lax oversight of the banking sector in relation to the fraud.
During the impeachment hearing, Hosseini received unexpected support from one of Ahmadinejad's main political rivals in the conservative camp -- parliament speaker Ali Larijani -- who said the legislature should "not create new conflicts" in the current political atmosphere.
No indication was given about the likely length of the trial.