Motorcyclists who cause chaos by taking part in so-called Halloween "ride outs" have been warned they will be dealt with "robustly" by police.
Scotland Yard has launched a crackdown on the events, after responding to large groups of bikers engaging in anti-social behaviour for the last two years.
The riders were intent on causing disruption across London by driving recklessly, on the wrong side of the road, through red lights and on pavements, the Metropolitan Police said.
Many of those taking part in the Halloween "ride outs" were also using stolen motorbikes, it added.
Superintendent Tania Coulson said the groups had put themselves and members of the public at risk with their behaviour in the past.
She said: "We know that some people may see the event advertised and think they are joining like-minded enthusiasts on a lawful ride. This is not the case. They drive ruthlessly and carry out stunts on the road.
"Officers will be out across London throughout the Halloween period and will deploy a number of police tactics to prevent riders from driving dangerously. We intend to prevent disorder and crime caused by riders and we will be dealing robustly with offenders. Any groups or individuals who cause disruption will be arrested."
The Metropolitan Police said it was aware that many individuals taking part in the "ride outs" were linked to the group "UK Bike Life".
Last year, several people were arrested after more than 200 motorcyclists gathered for a "Halloween ride-out" in Solihull and Birmingham.
At one point up to 100 masked bikers surrounded a police van in Yorkminster Drive in Chelmsley Wood, while the fire service also reported that a group had attempted to stop them from responding to an emergency call.
In Leeds a group of around 50 racing off-road motorcycles and quad bikes brought a busy road to a standstill, as part of an event believed to be organised on social media.