Iran's elite Revolutionary Guards warned the moderate opposition on Monday not to stage any rallies on Nov. 4, when the Islamic Republic marks the 30th anniversary of the seizure of the U.S. embassy in Tehran.
Opposition leader Mirhossein Mousavi, who says the June election that he lost to President Mahmoud Ahmadinejad was rigged, appeared to urge his supporters two days ago to take part in rallies on that day.
Referring to the Iranian date of the capturing of the U.S. embassy three decades ago, Mousavi said: "The 13th of Aban is a... rendezvous so we would remember anew that among us it is the people who are the leaders."
Several reformist websites are urging opposition supporters to gather on Wednesday and protest "peacefully" and not to resort to "violence even if they are attacked."
In mid-September, reformist supporters clashed with police and government backers at annual demonstrations in support of the Palestinians. Some reformist websites have called for renewed demonstrations on Wednesday.
The Guards, who helped to quell huge street protests after the election, called on the Iranian people to "exercise vigilance in regard to the likelihood of mischief and plots by the enemy's agents and some unaware and misguided (people) on Nov. 4", the official IRNA news agency reported.
"The Iranian nation will not allow any (political) group to impose itself and use diversionary and false slogans on Wednesday," it quoted a Guards statement as saying.
Capturing the embassy
Nov. 4 has emerged as an anti-U.S. day in Iran, with thousands of Iranians, mostly students, gathering annually outside the U.S. embassy building, dubbed the 'Den of Spies', to shout slogans such as "Death to America!" and "Death to Israel!"
The event marks the capture of the embassy on Nov. 4, 1979 -- just months after the Islamic revolution toppled the U.S.-backed shah -- by radical Islamist students who took American diplomats hostage for 444 days.
Since then, the event which was aimed at condemning U.S. policies towards Iran, has become one of the cornerstones of the Islamic regime.
The embassy compound in central Tehran, now run by the Revolutionary Guards, is used as an educational centre with occasional exhibitions highlighting the "crimes" of the United States.
Ahmadinejad's main rivals have rejected what they say is his "fraudulent victory" and their supporters have demonstrated at the slightest opportunity against the hardliner.
Opposition leader Mehdi Karroubi, who has alleged that several protesters were raped and beaten in jails in the immediate aftermath of the June election, is expected to participate in the annual event.
In the unrest that followed the June poll, security forces arrested some 4,000 protesters, reformists and journalists, while dozens were killed in the clashes.
Most of the detainees have been released but around 140 are being prosecuted, including some senior reformist politicians, in what opposition leaders have labeled "show trials."