Just Stop Oil (JSO) protests have cost police more than £3.5 million and nearly 11,000 officer shifts in the past month.
The Metropolitan Police revealed the figures as nine more JSO supporters were arrested on Wednesday during the group’s latest batch of road-blocking marches.
Campaigners have been staging protests every day since April 24, sparking confrontations with members of the public who are caught in traffic as the activists walk slowly in the road.
The £3.5 million is on top of the £7.5 million spent by the force dealing with JSO action between October and December last year.
Police now have powers to force them to move onto the pavement, but arrested the nine JSO supporters on Wednesday for allegedly failing to do so.
Met Assistant Commissioner Matt Twist said the time between officers arriving at each scene and imposing conditions to move protesters out of the road is between 13 and 19 minutes.
He said: “A short period of engagement and assessment after officers first arrive at each scene is unavoidable, but where we conclude that serious disruption is occurring we are intervening without delay to get traffic moving again.”
One man was handcuffed by police after appearing to push two JSO supporters out of the road on Blackfriars Bridge on Tuesday.
The group said a motorcyclist tried to drive through the demonstrators, and in a separate incident a van crashed into a bus stop as the driver tried to get past the activists.
Other members of the public were said to have grabbed banners.
On Friday a man approached JSO protesters as they marched slowly in front of traffic on Mansell Street, near the Tower of London, before snatching their banners and pushing a woman to the ground.
“I would urge the public not to intervene or take matters into their own hands, but to call the police, let us know where the incident is and we will get there quickly.
“I know that a widely shared video of a member of the public confronting protesters on May 23 has reignited the strongly held public feelings about this protest tactic and how we are responding to it.
“But we must recognise that short clips of individual incidents don’t tell the whole story of a much larger policing operation which, as we have shown, is ensuring that our response times are effective and that our interventions are seeing roads cleared with minimal delays.”
JSO is staging what it calls “an indefinite campaign of civil resistance” to end all new oil, gas and coal projects in the UK.