Protester put pre-Islamic revolution Iran flag on London embassy: witnesses

A video posted to social media showed a man on the balcony of the embassy, near Hyde Park, replace the country's current flag with one used during the rule of the ousted shah to cheers from hundreds of demonstrators below.

The flag -- tri-coloured, with a lion and sun, surrounded by a wreath and crown -- was a ceremonial one used in Iran before the Islamic revolution.

It stayed in place for several minutes before being removed, witnesses on site told AFP.

"Democracy for Iran. Shah Reza Pahlavi. Justice for Iran," chanted the demonstrators, referring to the son of the late shah of Iran who now lives in the United States. Some also held placards reading "Free Iran".

"I'm here to support Iranians, my loved ones inside Iran -- they've been protesting for two weeks today," said one demonstrator, Taraneh, 33, who declined to give her last name.

"The internet has been shut down ... We get very little information from inside Iran," she added.

"But, you know, people are still in the streets. They're being attacked. The Islamic Republic is murdering people," she said. "I want this regime to go. I just want to be able to go back."

London police, in an online post, said that after the flag incident "additional officers are being deployed to prevent any disorder" and to protect the Iranian embassy.

They said they had arrested two people, "one for aggravated trespass and assault on an emergency worker and one for aggravated trespass" and they were seeking another another individual for "trespass".

Iran has been roiled by street protests since December 28, which have since taken hold nationwide.

Initially triggered by a devaluation of the country's currency and growing concerns over the cost of living, they have since spiralled into mass demonstrations calling for an end to the Islamic Republic.

Iranian authorities have cut off internet access in the country, and NGOs and monitoring organisations say they fear that blackout will be used to crack down on the protesters.

At least 51 people have been killed so far, including nine children, with hundreds wounded, according to the Norway-based NGO Iran Human Rights.