Scotland Yard today warned of the risk of violence at this weekend’s bonfire night Million Mask March amid growing fears it could descend into chaos.

Clad in V for Vendetta masks, thousands of activists are set to descend on central London on Saturday for the annual protest organised by activist group Anonymous.

Police announced a series of restrictions on the event this evening and said officers believe “peaceful protest is the last thing on the minds” of those who plan to attend.

Last year's march saw ugly scenes as missiles and fireworks were thrown at police. Four officers and six police horses were injured and 50 people arrested.

Chief Superintendent Pippa Mills said the force had “serious concerns” about a repeat of last year’s disorder.

She said in a statement: “We will always facilitate peaceful protest and have a strong history of doing so. However we have strong reason to believe that peaceful protest is the last thing on the minds of many of the people who will come along this year.

“Criminality at the event has increased year-on-year. Last year hundreds of Londoners on their way home from work, or out enjoying an evening in the Capital, were harassed and intimidated by people causing them huge concern. Public property was damaged, businesses had windows smashed and police officers and horses came under attack.

“Those who choose to behave like this are not protestors, they are committing criminal acts.”

But the protest’s organisers appeared to be putting on a defiant front, posting on their Facebook page: "the police are not your friends".

Police have imposed conditions on the march, limiting it to a three-hour period between 6pm and 9pm on a prescribed route between Trafalgar Square and Whitehall.

Any static protest must only take place in Trafalgar Square, Richmond Terrace and Parliament Square and the Met warned anyone breaching the conditions could be arrested for public order offences.

Chief Superintendent Pippa Mills said: "We will always facilitate peaceful protest and have a strong history of doing so. However we have strong reason to believe that peaceful protest is the last thing on the minds of many of the people who will come along this year.

"Criminality at the event has increased year-on-year. Last year hundreds of Londoners on their way home from work, or out enjoying an evening in the capital, were harassed and intimidated by people causing them huge concern.

"We have such serious concerns about a repetition of such criminal behaviour this year that we have made the decision to impose conditions under the Public Order Act on the event on Saturday 5 November."