The HGV is “fully alight” on the M25 anticlockwise between Junction 25 and Junction 24, with the anticlockwise carriageway closed to traffic.
Firefighters were called to the blaze just before 1pm today (January 16) and are currently fighting the flames.
The clockwise carriageway was also closed due to this incident but was re-opened at approximately 3pm.
Videos taken by motorists stuck in nearly an hour of traffic show the fire and attempts to bring it under control.
One clip shows plumes of black smoke pouring from the vehicle while others show the queue of cars trailing from along the motorway.
National Highways has warned drivers to allow extra time, re-route or even to delay their journeys.
A London Fire Brigade spokesperson said: “Firefighters are in attendance at a lorry fire on the M25 Westbound between Junction 25 and Junction 24.
“The lorry is fully alight. Control Officers took the first of 15 calls at 1255.
“Two fire engines are in attendance alongside fire engines from Hertfordshire Fire and Rescue Service.”
