Thousands of demonstrators poured into the streets of Tehran and other cities, chanting slogans against the government, Sahamnews reported.
"Security forces and plainclothes agents fired teargas and clashed with demonstrators in Tehran to disperse them," another opposition website Kaleme reported.
"Protesters have formed groups in hundreds and are marching toward Tehran's Azadi (Freedom) Square." Potesters demanded the release of Mirhossein Mousavi and Mehdi Karroubi
, forced to stay in their homes in Tehran since February 14. In the meantime, thousands of their supporters have taken to the streets, defying a heavy security presence, to back uprisings in Egypt and Tunisia, Sahamnews said.Seeking to avoid a revival of mass anti-government rallies that erupted after a disputed 2009 presidential election, the authorities had warned against any "illegal" gatherings after some opposition websites posted calls for a rally on Tuesday.
"Riot police attacked protesters with batons and electric shocks in Tehran," Kaleme reported.