Severe delays are currently building near Potters Bar and the A1(M) on the M25 following a four-vehicle crash.
The collision on the clockwise carriageway at about 6am has caused Highways England to close the M25 between Junction 23 for South Mimms and the A1(M) and Junction 25.
It is currently unclear if anyone was injured.
Emergency services are currently on the scene and motorists are being advised to use other routes where possible.
More follows.
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