The M25 near London Colney is currently blocked in both directions after a lorry caught fire.
The blaze started just after midday between junctions 22 for the A1081 and 21A for the A405 near St Albans.
Fire crews from Potters Bar, Borehamwood and Garston have now extinguished the fire on the anti-clockwise carriageway.
Traffic was stopped on both carriageways at about midday. There are no reports of casualties.