Tens of thousands of Iranians took to the streets of Tehran again Wednesday to protest the results of last week's controversial election.  Iranian authorities have banned such gatherings, but analysts in Britain, say they expect the crisis to continue.

Protests in Iran surrounding the controversial re-election of President Mahmoud Ahmadinejad continue as defeated candidate Mir Hossein Mousavi called on his supporters to stage peaceful demonstrations.

The protests are widely seen as a direct challenge to the government, which has banned the gatherings.

Amateur videos and earlier television reports from Tehran showing masses of protesters, who in some cases were beaten and killed, have sparked a debate over just how serious the challenge to the government is and how long it can last.   

Professor Ali Ansari is director of the Institute of Iranian Studies at the University of St. Andrews in Scotland. Speaking Wednesday in London, Ansari said the scale of the protests is unprecedented and, he said they will likely continue.

"I think we are in for a long hot summer. I don't think it's going to end quickly. I think the hardliners will fight trench by trench and it will depend on the other side really maintaining the momentum," he said.

Iranian authorities have already cracked down on media coverage of the protests. On Wednesday the Revolutionary Guard warned Iranian Web sites against publishing materials that create tension. Journalists from foreign news organizations are also banned from venturing out to cover the unrest.

But Professor Ansari said he believes the crackdown is counter productive.

"One of the questions about the demonstration on Monday, for example, is how large was this crowd? I have never known how you count a crowd. But the point is, it is what people believe. And what people believe is this was extraordinary large and the largest crowd on the streets since 1978. This is what I mean by the crisis of authority, the government can say any number of truths now and nobody will believe them," he said.

Challengers have accused Mr. Ahmadinejad of election fraud, and Iran's Guardian Council has said it will recount some of the ballots from Friday's vote.

But Professor Ansari said a recount will not be seen as credible.

"The argument is doing a recount, a selective one, or even a complete one, would be something people would have issues with particularly because they are claiming many of their potential voters weren't even allowed to cast their vote," he added.

Ansari describes any recount as a delaying tactic by the authorities who are hoping things will calm down.

The ongoing unrest in Iran is being closely watched around the world and thus far western leaders have reacted with guarded criticism.

In Washington, President Barack Obama has expressed "deep concern about the election" but was careful to point out that the U.S. must not be seen as "meddling."

Former British Ambassador to Iran, Sir Richard Dalton agreed.

"The United States interest is to avoid putting itself in the middle of this Iranian domestic dispute," said Dalton.

President Obama said he will continue to pursue a direct dialogue with Iran, and Dalton said after the dust settles, it is in Iran's best interest to explore negotiations with the United States.