A police motorcycle rider was injured as officers responded to a Just Stop Oil protest on the M25.
Essex Police said there was a collision involving the motorbike and two lorries during a rolling roadblock introduced due to an activist on the motorway between Junctions 26 and 27 on Wednesday morning.
Home Secretary Suella Braverman said: “My thoughts and best wishes go to the Essex Police officer injured while dealing with protesters engaging in guerrilla tactics on the M25 today.
“These protests are dangerous and I fully back police in using all tools available to prevent further disruption and protect the public.”
Chief Superintendent Simon Anslow, of Essex Police, said his officers “responded quickly”, and one was injured “as they worked to help resolve this situation”.
He went on: “Our roads policing officers are dedicated, specialist officers who come to work to serve the public and keep you safe on our roads.”
Just Stop Oil said in a statement: “The collision of two lorries and the injury of a police officer on the M25 this morning is an awful situation.
“The level of disruption being witnessed on the M25 should not be happening – people are rightly angry and frustrated.”
It added: “The failure of our politics has left us with no other option as we seek to protect our rights and freedoms from a collapse in law and order due to a heating world.
“The Government can end this, immediately, by ending dirty new oil and gas.”
Members of Just Stop Oil have been joined by activists from Animal Rebellion, a group campaigning for “a plant-based food system”.
The Metropolitan Police said one person had locked themselves on to an overhead gantry near Junctions 24 and 25.
The force said: “Locks add more complexity for our removal teams and the overall process becomes longer.
“We have had to bring in specialist equipment for this removal, including a JCB.
“Officers will endeavour to work swiftly and safely to open as quickly as possible.”
Just Stop Oil staged 32 days of disruption from the end of September and throughout October, which the Met said resulted in 677 arrests with 111 people charged, and officers working a total of 9,438 additional shifts.
According to Just Stop Oil, its supporters have been arrested more than 2,000 times since its campaign began on April 1, and 15 are currently in prison.
Chairman of the National Police Chiefs’ Council Martin Hewitt told the body’s joint annual conference that police are not anti-protest but are “pro-responsibility”.
He said: “This week we are seeing protests on the road network. A combination of proactivity and preparedness meant we have been able to reopen the busy motorways quickly.
“Working with Government and other agencies, we continue to use civil injunctions as well as our criminal powers to minimise disruption.”
He added: “Policing is not anti-protest, but we are pro-responsibility and for having due regard for the rights of others.
“We will continue to take all appropriate action against anyone who deliberately chooses to protest outside of the law.”
Speaking to journalists after his conference speech, Mr Hewitt said some protest groups are increasingly using “dangerous” tactics.
“We are increasingly seeing things that are dangerous – dangerous for the protesters, dangerous for other members of the public and, as we’ve seen this morning, dangerous for police officers,” he said.
“I just think that all of those groups, who have every right to make the point they want to make, have every right to seek to get that point through the media, need to think really hard about the responsibility that they have both to themselves, to other members of the public and to, as we’ve seen, police officers that are that are having to go there and try and deal with these very difficult circumstances.”