A serious accident involving two vehicles has left severe delays around the Barnet bypass.
The A1 northbound in Borehamwood, between Stirling Corner and the M25 junction, was closed earlier following an accident involving a car an a lorry.
Two lanes have now been reopened, however there are still severe tailbacks from Mill Hill Circus and Fiveways.
Both police and a number of fire engines are in attendence at the scene, which occured at the slip road going north from Borehamwood.
More to follow