Just Stop Oil have said the collision of two lorries and the injury to a police officer on the M25 that resulted from their protests is an "awful situation".
The group calling for an end of new oil and gas said in a statement that people are "right" to feel "angry and frustrated" about the group's tactics that are causing disruption for many across Britain.
The group is calling on the Government to commit to no new oil and gas. Just Stop Oil
In a statement posted to their website, they said: "The impact on peoples lives is huge. In normal circumstances this would be unacceptable.
"It should never have come to this. 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.
"The failure to abandon this toxic policy is a failure of politics and failure of leadership, it is a betrayal of us, our children and this country."
It comes after a police motorcycle rider was injured as officers responded to their protest on the M25.
The group's tactics caused widespread disruption on the M25. Just Stop Oil
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.
Just Stop Oil said around 10 of its supporters climbed on to overhead gantries in “multiple locations” on the M25 from 6.30am, in what is the third consecutive day of protests on the UK’s busiest motorway.
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.”