Yazdi, a former foreign minister, was arrested in the city of Isfahan along with several other members of the Freedom Movement of Iran.
He was also detained in June 2009 during a wave of unrest which followed the disputed re-election of President Mahmoud Ahmadinejad that the opposition in the Islamic republic said was the result of massive fraud.
IRNA also said Yazdi, who served in the first government following the 1979 Islamic revolution that overthrew the shah, had announced his resignation as head of his party, without giving a reason.
Meanwhile opposition websites said at least 20 opposition figures arrested in the past two years and sentenced to long prison terms had been released to pass the Iranian new year holiday commencing Monday with their families.
They will have to return to jail when the holidays end at the beginning of April.
Thousands of people were arrested in demonstrations against Ahmadinejad in 2009 and dozens were sentenced to prison terms, including political opponents of the president, journalists and other activists. (M014/K004)
Editor: Kunto Wibisono
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