Leaders of Iran's opposition movement are to make an unprecedented apology to the US on the 30th anniversary of the storming of the American embassy in Tehran.
In a gesture likely to provoke fury among hardliners in the Tehran regime, they will apologise on Wednesday for the hostage crisis that gripped the world for 444 days and led to a decisive break between Iran and the US, which is now routinely denounced as "the Great Satan".
Organisers of the Green Movement, the umbrella group that seeks to overturn the official result of the June presidential election, plan to use the official commemoration of the take over to make a fresh assault on the revolutionary credentials of Iran's leadership.
Mohsen Makhmalbaf, an exiled film-maker who spearheads the opposition campaign overseas, said Iranians should repudiate the events of 1979, when a group of pro-regime agitators took over the US embassy and held diplomats and other occupants.
"Thirty years ago in the turmoil of the revolutionary zeal an indefensible act of hostage taking was committed that the new generation of Iran are not proud of at all," he said. "We know very well how that deplorable action hurt the noble American people and how it led to three decades of unnecessary and painful bad relations between our two nations.
"Only a small and repressive minority who rule Iran today still insist on keeping Iran on a confrontation course with the US, Britain and the West and indeed they have now taken the Iranian people as hostage to their destructive policies."
Protesters plan to deliver a letter addressed to President Barack Obama to the US embassy in London and deliver commemorative plaques to American embassies across Europe.
Student's Day is marked every Nov 4 by large crowds outside the embassy building celebrating the takeover of the "Den of Spies" and shouting slogans such as "Death to America" and "Death to Israel".
But an internet-based campaign has circulated a series of posters calling for infiltrators to denounce President Mahmoud Ahmadinejad's re-election. The president's challengers, including the former prime minister, Mir-Hussein Mousavi, have demanded a re-run of the election, which was marred by ballot tampering.
Iran has outlawed opposition rallies and the use of violence by regime supporters has quashed open shows of defiance. The hardline response ordered by Ayatollah Ali Khamenei, Iran's Supreme Leader, resulted in the deaths of at least 30 protesters and the detention of thousands. An estimated 200 opposition activists remain behind bars and three have been sentenced to death.
But the tactic of using official holidays as cover has proved to be an effective means of challenging the regime. A day of solidarity with the Palestinians was similarly hijacked in September.
By expressing regret for the embassy takeover, the opposition is taking on the most cherished event in the first months of the Islamic Republic. The confrontation was to define the new state. Tehran's defiance of America means it remains incapable of resolving a stand-off over its secret nuclear programme.
Ahmad Reza Radan, the deputy chief of Iran's police, has warned that counter-demonstrations would be put down.
All I can say is, my heart is with the freedom fighters in Iran, and I wish with all my heart we had a President with the backbone to support you.
Oh, for the days when we stood for something; for a time when we believed in more than just saying "nice doggie" to nutjobs like Ahmadinejad. We desperately need someone who will call a spade a spade. Ronald Reagan, where are you?