Iranian opposition leader Mehdi Karoubi, defying government warnings, said the Islamic Republic was "plagued with despotism," in remarks published ahead of a national celebration that could trigger more protests.
"Unfortunately the current republic is plagued with despotism and elections have become meaningless," Karoubi, a moderate cleric and former parliament speaker, said in comments to a group of students carried on his website on Tuesday. On Sunday radical elements attacked his home in Tehran and urged to indict him.
"This government has not been formed upon the people's votes, and the result has been social unrest."
Iran has experienced the worst domestic strife since the 1979 revolution after supporters of Karoubi and opposition candidate Mirhossein Mousavi took to the streets to protest against the victory of President Mahmoud Ahmadinejad last June.
The opposition says the vote was rigged to secure the re-election of the hardline president. The authorities deny the charge of vote fraud and say it was the healthiest election the country has had in three decades.
A crackdown on the opposition was expected on Tuesday when Iranians hold celebrations a few days before the country's New Year which starts on March 21.
Police chiefs have strongly warned the opposition against using the occasion to organize fresh protests and, in an attempt at deterrence, have said that anyone arrested on that day will be held until the end of the Iranian new year holidays.
Most of those detained after the election have since been released, though more than 80 have received jail sentences of up to 15 years. Two people who were put on trial after the election have been executed.
Dudi Cohen contributed to this report