Thousands of drivers are suffering severe delays because of two closures on the M25, including part of the Dartford Crossing.
The motorway is closed in the clockwise direction between Junction 5 in Kent and Junction 6 in Surrey because of a lorry fire.
Meanwhile, the northbound east tunnel of the Dartford Crossing between Kent and Essex is also closed, after a maintenance vehicle breaking down caused a large spillage.
Both closures are causing several miles of congestion and are expected to remain in place throughout Monday.
The lorry fire happened in Surrey between Clacket Lane service station and Junction 6 late on Sunday night.
Surrey Fire and Rescue Service said at around 7am on Monday that one fire engine remained at the scene, with the crew damping down hot spots.
The motorway was initially closed in both directions between Junctions 5 and 6 while firefighters tackled the blaze.
National Highways said shortly after 3am that two out of four lanes of the anti-clockwise carriageway were reopened.
But it warned the clockwise carriageway is "likely to remain closed throughout the day."
This is because specialist equipment is needed to remove the lorry, and the road is likely to require resurfacing.
There were four miles of congestion and 45-minute delays on approaches to the scene, National Highways said at 9am.
A diversion involving A roads is in place.
Meanwhile, a separate incident at the Dartford Crossing between Kent and Essex is also causing major congestion.
National Highways said the northbound Dartford east tunnel is closed as overnight roadworks overran because a maintenance vehicle broke down within it, requiring emergency resurfacing works.
It said there is a “large spillage within the tunnel”, which will “remain closed throughout the day”.
The Government-owned company added: “There are severe delays on all approaches.”
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