_{An Iranian opposition supporter covers his face with a bloodstained hand during clashes with security forces in Tehran on 27 December 2009. Photograph: Getty Images}

The wave of arrests that erupted in Iran yesterday marks the latest move by a government determined to silence growing opposition despite the spiralling political crisis in which it finds itself.

However, it seems that the arrests, along with the killing on Sunday of eight protesters, including a nephew of the Reform presidential candidate, Mir Hossein Mousavi, will instead make martyrs out of mere men. The developments are also catalysing a movement that increasingly sees the regime of the Islamic Republic's supreme leader, Ayatollah Ali Khamenei, in the light of the former, much-hated shah.

Ali Mousavi's death is especially significant, given that the violent crackdown on Sunday's protests in Tehran coincided with the Shia holiday of Ashura, a mourning event that remembers Iman Husayn, a grandson of the Prophet Muhammad martyred in the year 680. Mousavi's body has since been seized, a move that analysts in Tehran have suggested is an attempt to prevent demonstrations from forming around his funeral.

Fatemeh Haghighatjoo, a former member of Iran's parliament who is currently a visiting scholar at the University of Massachusetts, told the New York Times:

Ashura is a very symbolic day in our culture and it revives the notion that the innocent were killed by a villain.

Similarly, Juan Cole, president of the Global Americana Institute, remarked:

For the regime to create a member of the Mousavi family as martyr on Ashura was most unwise. Shiite Islam even more than traditional Catholicism thrives on the blood of martyrs.

The arrests have only served to further villianise the regime. At least seven leading opposition activists have been arrested, including the opposition politician Ebrahim Yazdi, a foreign minister after the revolution, and three aides to Mousavi, prompting bloggers to label yesterday the "Iranian Night of the Long Knives".

More critically, Ayatollah Khamenei's legitimacy, already damaged by his support for Prime Minister Ahmadinejad's re-election in June, has been hardest hit by the government's decision to repress. Although he still commands the loyalty of the Revolutionary Guard, new hatred for him has sprung up among Iranian elites and the opposition is now more unlikely than ever to back down.

Writing on his website, the Iranian film-maker Moshen Makhamalbaf was one of those who denounced Khamenei for Sunday's violence by comparing him to the the shah (translation taken from the New York Times):

I am so sorry that I fought against the shah when I was 17. He left the country when he realised that people no longer wanted him. But you are resisting until everyone else leaves the country.