There are severe delays of up to 2 hours on the M25 anti-clockwise between junction 9 and junction 5 because of an overturned vehicle and a fire. Lanes 2,3 and 4 (of four) were reopened just before 6pm.
Drivers joining the M25 intending to travel anti-clockwise form the M23 and A23 are also affected. Highways England are advising travellers to consider taking alternatives routes, and to allow extra time for their journeys.
A new report says congestion on the M25 is so bad the region's economy is at risk and urgent action must be taken.
The report by Highways England found the stretch of motorway between the A3 in Surrey and the M40 in Buckinghamshire had the worst traffic in Europe with more than 220 thousands vehicles using it every single day.
In a highly controversial move it says key roads in Berkshire, Buckinghamshire, Surrey and Hampshire should be improved to cope with the growing problem.
This report is from our Transport Correspondent Mike Pearse.
A new report commissioned for the Government has found that the 'rush hour' for drivers using the M25 can actually last from 6am to 6pm.
The finding is a surprising one to many, but some transport campaigners say that people who use the M25 already know that there is a lot of traffic on the route.
The Department for Transport says that it is spending a lot of money on improving the south's major routes.
Campaigners working for the improvement of our road networks in sustainable way have welcomed a new report about travelling on the M25, and other routes in the region.
There is queueing traffic and there are intermittent lane closures on the M25 anticlockwise at the Dartford Tunnel. There is congestion on the M25 to J2 A2 (Darenth Interchange). The measures are being put in place to prevent queueing in the tunnels.
Overnight works have overrun at the Dartford Tunnel. There is queueing traffic and there are intermittent lane closures on the M25 anticlockwise at the Dartford Tunnel.
There is congestion on the M25 to J2 A2 (Darenth Interchange). There are also the usual restrictions to prevent queues inside the tunnels with ongoing A13 works at J30.
One lane closed and busy but moving due to accident on M25 anticlockwise between J11 A317 (Chertsey) and J10 A3 (Wisley Interchange).
Kenneth Noye - jailed for the murder of Stephen Cameron on the M25 in Kent - will learn in the next few days if he's to be released from prison.
The 68-year-old year-old career criminal had his parole hearing today after serving 15 years of a life sentence.
Before the 'road rage' murder of Mr Cameron, Noye served 14 years for conspiracy to handle bullion from the £26m Brink's-Matt robbery in 1983.
Two lanes closed and queueing traffic on M25 anticlockwise at the Dartford Tunnel, congestion to J2 A2 (Darenth Interchange).