Four fire engines and around 25 firefighters tackled a fire involving a lorry on the M25 between Junction 25 and Junction 24 in Enfield.
The lorry was carrying bales of hay, which were partly damaged by the fire. There were no reports of any injuries.
A full road closure was put in place on the anticlockwise carriageway. Some lanes remain temporarily closed and motorists can expect traffic disruption.
Control Officers took the first of 15 calls at 0526 and mobilised crews from Enfield fire stations to the scene. Two fire engines from Hertfordshire Fire and Rescue Service also attended the scene. The incident was over at 0841.
The cause of the fire is under investigation.