Drivers are facing queues of up to four miles on the M25 near Enfield following two separate incidents, a vehicle fire and collision, which has caused three out of four lanes to close on Thursday morning. Normal traffic conditions are not expected to resume until around 1:30pm.
Lanes closed at Junction 24 and Junction 25 have been shut by the police.
Further queues have also been reported on the clockwise stretch of the motorway at the same junction after a vehicle set on fire – causing queues of up to six miles leading up to the incident.
Pictures taken from traffic cameras show a big emergency service presence at the scene.
Police, ambulances and fire engines are attending to the scene.
The accident reportedly happened on Thursday morning on the M25 clockwise from Junction 24 A111 Stagg Hill to Junction 25 A10 Great Cambridge Road, near Enfield.
Lane one remains the only open lane for traffic, as of 10:40am.
It is not yet known if there have been any injuries.
Normal traffic conditions are expected to resume between 1:30pm and 1:45pm.
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National Highways England confirmed Junction 26 and Junction 25 are blocked anti-clockwise due to a van fire in the carriageway.
The Fire and Rescue Service is on the scene attending to the vehicle fire.
CCTV footage shows lanes two, three and four closed with a fire engine located on the highway, surrounded by billowing black smoke from the blaze.
National Highways warned drivers to take care on the approach to the incident.
Drivers are also told to expect long delays following the two incidents located just a few miles from each other on the M25.
Traffic is heavier than normal on the A406 North Circular and there is also congestion between Hall Lane (Cooks Ferry Interchange, Edmonton) and A105 Green Lanes (Clockhouse Interchange, Palmers Green).
There is also two miles of traffic on the M25 between J25 A10 (Enfield) and J24 A111 Stagg Hill (Potters Bar) as well as congestion to the Holmesdale Tunnel before the J25.
Traffic website Inrix confirmed the two separate incidents are a vehicle fire and a collision.
The Met Police have confirmed that no injuries have been reported following the incident.