Emergency services have closed the motorway between junction 21A and 22
A large fire has broken out next to the M25, forcing the motorway to close as firefighters tackle the blaze.
Emergency services are at the scene in St Albans after the fire started at an industrial estate in Ventura Park.
Pictures on social media and released by National Highways show thick dark smoke rising above the carriageways, with road closures in place.
Commuters have been warned that there are currently delays of around 60 minutes in both directions as a result of the fire.
Due to the risk of secondary explosions, along with smoke and debris affecting the carriageway, the motorway remains closed as a precaution, National Highways said.
Given the incident’s proximity to a railway line, the Network Rail also have a representative on site to liaise with the fire service.
A Hertfordshire Fire and Rescue Service spokesperson said: “We are currently responding to an incident in Ventura Park, Old Parkbury Lane, Colney Street, St Albans.
“If you live locally, we advise to keep doors and windows closed and please avoid the area while emergency crews carry out their work.”
Deputy Chief Fire Officer Mark Barber said firefighters are “working hard to bring the situation under control”.
He said: “Fire Control has received a significant number of calls regarding this incident, and I would like to reassure residents that firefighters are working hard to bring the situation under control.”
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