While thousands are taking to the streets in Iran today to mark the 31st anniversary of the revolution, the Iranian opposition movement is planning to hijack official celebrations despite threats of a widespread crackdown.
Human rights activists, political groups and the 'Green Movement', which called for its supporters to take part in the 11 February events, have already faced restrictions on phone and internet networks.
Police and pro-government militia are also reported to be preventing many who may be opponents of the current regime from joining the rally in Tehran. There is heavy security to prevent opposition protests.
The son of Mehdi Karroubi, one of the defeated reformist candidates in the disputed 2009 presidential poll, has told the news network Al Jazeera that this father's car was attacked by security forces on his way to the rally.
The opposition Jaras website reports that Karroubi was not seriously hurt when the windows of his car were smashed. Mohammed Khatami, a former president, has also been attacked, some sources inside and outside the country say.
Alireza Ronaghi, Al Jazeera's correspondent in Tehran, said: "The government really doesn't want any violence today, but it is not going to tolerate any kind of demonstrations with symbols of the opposition. We have heard from elsewhere in the city that opposition demonstrators who were trying to join the rally had been stopped on their way by security forces."
Ayatollah Khomeini's grand-daughter, Zahra Eshraghi and her husband, Mohammad Reza Khatami, have been arrested on the 31st anniversary of the revolution, sources told Al Jazeera.
The security forces are preventing the people from reaching Enghelab and 7 Tir Squares and clashes have been reported around Baharestan Square, according to a new live blog in English and Farsi from http://astreetjournalist.com
The Guardian newspaper is running a live blog on developments in Tehran and elsewhere in Iran: http://www.guardian.co.uk/news/blog/2010/feb/11/iran-protests-22-bahman
The Iranian Revolution took place in 1979. The Western-backed Shah Mohammad Reza Pahlavi was overthrown and Ayatollah Khomeini returned to the Persian nation to become the leader of a new Islamic Republic.
In mid-January that year, after months of demonstrations, the Shah went into exile. Two weeks later, the Ayatollah returned to Tehran from France. In October 1979 the Shah was admitted into the USA for cancer treatment. At that time many in Iran were calling for the Shah’s return and for him to stand trial for his crimes, with anger being directed at the United States.
Then on 4 November Muslim students stormed the US embassy in Tehran and took 52 American diplomats hostage. The hostage crisis lasted for over a year and was ended only after the defeat of US President Carter and the victory of Ronald Reagan in 1980 - with the new Iranian regime using it as a tool to humiliate their US opponents.
The Islamic regime is Tehran has been accused of the widespread violation of human rights, the violent suppression of opposition, and the denial of democracy. A fresh opposition movement has been growing in Iran over the past year.