A police officer has been injured while responding to a report of people trying to gain entry to gantries on the M25 while a Just Stop Oil protest was taking place.
Essex Police said one person was arrested as officers intervened to deal with a protester on the motorway between Junctions 26 and 27.
A rolling road block was put in place as police attempted to deal with the protests and there was a collision involving two lorries and a police motorbike.
There have been further reports of people on gantries near to Junctions 29 and 30.
Chief Superintendent Simon Anslow said: “Officers have again responded quickly to minimise disruption and two people have already been arrested.
“One of our officers has been injured as they worked to help resolve this situation.”
The incident has led to road closures between Junction 26 and Junction 27 clockwise.