A silent sea of black-clad mourners made its way through the streets of Tehran this afternoon, commemorating the lives of those slain in six straight days of protests since the announcement of President Ahmedinajad’s election victory.

The scenes recalled the mass mourning protests of the 1979 Islamic Revolution, when hundreds of thousands took to the streets to play their part in the overthrow of the American-backed Shah.

Tens of thousands of demonstrators marched silently until they reached Iman Khomeini square, the huge plaza named for the founder of the revolution, where they were joined by Mir Hossein Mousavi, the defeated opposition candidate.

The crowd broke into chants, shouting “Death to the Dictator!” and “where are our votes?” as Mr Mousavi addressed them, repeating his calls for a fresh ballot to replace a result widely seen as fraudulent.

At least seven people were killed in violence that erupted during Monday’s massive protest, when militiamen attacked and opened fire on protestors demanding that their “stolen” votes be counted. But persistent reports indicate that more may have been killed in both Tehran and Shiraz and buried quickly without official recording.

Protestors dressed in black for mourning - a change from the usual green worn by Mousavi supporters - and carried placards remembering the dead. “We have not had people killed to compromise and accept a doctored ballot box” read one; another “My martyred brother, I will get back your vote."

Some protesters carried pictures of footballers from Iran’s national team wearing green wrist-bands in their World Cup qualifier against South Korea last night. Passing motorists sounded their horns in support as the marchers stopped to let them pass.

The march and rally took place despite a ban issued by the Interior Ministry, which backs the hardline incumbent, Mahmoud Ahmadinejad, who claimed victory in the polls with 63 per cent of the ballot. That figure is widely believed to have been doctored, with official results showing Mr Mousavi heavily defeated in his own hometown and also in Tehran, where his support is at it highest.

Mr Mousavi, who claimed he was the real victor, has dismissed the June 12 election as a “shameful fraud” and called for a re-run, with the backing of reformists, including some powerful clerics. Many protesters carried white flowers and placards reading: “We cried for Gaza, who cries for us?”

The fourth consecutive day of protests came in open defiance of Iran’s supreme leader, who has urged the people to pursue their complaints within the limits of the cleric-led system.

In a bid to ward off further protests, Iran’s Guardian Council invited Mr Mousavi and two other opposition candidates to a meeting on Saturday to discuss their grievances.

The unelected body of 12 clerics and Islamic law experts close to Ayatollah Khamenei said it was prepared to conduct a limited recount of ballots at sites where candidates claim irregularities. Mr Mousavi, however, has demanded an independent investigation and a new election, charging that the Council is too close to Mr Ahmadinejad to be trusted with the task.

The Council has received a total of 646 complaints from the three candidates, raising the possibility that even a limited recount could turn into a far larger and messier exercise than the government intended.

The crisis presents one of the gravest threats to Iran’s complex blend of democracy and religious authority since the system emerged out of the Islamic revolution that brought down Shah Mohammad Reza Pahlavi.

The ruling clerics still command deep public support and are defended by Iran’s most powerful military force - the Revolutionary Guard - as well as a vast network of militias.

But Mr Mousavi’s movement has forced Ayatollah Khamenei into the centre of the escalating crisis, questioning his role as the final authority on all critical issues.

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