Just Stop Oil: Protesters force sections of M25 to be closed
Protesters climbed signs above the M25, forcing police to shut sections of the motorway and to close lanes.
Five Just Stop Oil campaigners scaled three gantries, including at Heathrow and the Dartford Crossing, where sections of the motorway were closed.
They also targeted a sign near Cobham, Surrey, but by late afternoon all the protesters were moved on and the only closure in place was at the crossing.
Just Stop Oil said it was declaring the M25 "a site of civil resistance".
It also warned it would carry out further protests on the motorway in the coming days.
Five people have now been arrested.
A 22-year-old woman was apprehended by Surrey Police on suspicion of causing a danger to road users, causing a public nuisance, and for being a pedestrian on the motorway.
Essex Police said officers also arrested a woman, and Scotland Yard said officers apprehended three more people - two women and a man - on suspicion of causing a public nuisance.
The protests at the Poyle interchange between junctions 14 (Heathrow) and 15 (M4), and in Dartford between the Queen Elizabeth Bridge northbound and junction 30 (Thurrock), saw local police shutting two clockwise sections and putting diversions in place.
National Highways said five miles of queuing traffic had built up on the approach to junction 30 in Essex.
Surrey Police had earlier closed three lanes at Cobham and advised motorists to avoid the area around junction 10. The lanes have since been reopened.
Highways England said all protesters had been removed from the gantries during the course of the day, but a safety inspection was needed at a gantry near the Dartford Crossing before the motorway can be fully reopened.
Bus driver Ashley Reid said he was held up as he took children aged seven to 10 with special needs to a school in Leatherhead, Surrey.
He said his pupils, who were due to start at 09:15 BST, were about 90 minutes late for their last day of term.
"We joined [the motorway] just after 9am and we didn't arrive at school until 10:45am" he said.
"With their autism [they] found it difficult to understand and stay calm."
Just Stop Oil's statement said it chose the M25 as it was "the place where we confront the carbon economy headlong and bring our resistance into full public view".
It added: "The M25 has a kind of iconic status as the motorway from hell, doesn't it? So it's a reference to that".
The group is demanding the government make a "meaningful statement" it will commit to stop licensing and consents for the exploration, development and production of fossil fuels in the UK.
A government spokesman said: "We will not bend to the will of activists who naively want to extinguish North Sea oil and gas production.
"Doing so would put energy security and British jobs at risk, and simply increases foreign imports, whilst not reducing demand.
"We are committed to a strong North Sea industry as we transition away from expensive fossil fuels over the coming decades, and our recent British Energy Security Strategy sets out a long-term plan to ramp up cheap renewables and nuclear energy."
Just Stop Oil said it plans to hold further actions against oil infrastructure with trade unions, environmental groups and civil society organisations in the coming months.
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