Update: the road reopened last night after being closed for about an hour from around 7.15pm. More information will follow once verified with police.

DRIVERS are being urged to avoid part of the M1 tonight as police have closed it to deal with an "ongoing incident".

At this stage it's unclear what the incident is but motorists are advised the M1 is currently shut between Watford and St Albans northbound.

Update (August 21): police confirmed they were searching for a car thief who abandoned his vehicle on the A405 near the M1 and threatened other drivers. Full details here.

The motorway is also closed southbound  between junction 8 at Hemel Hempstead and junction 5 at Watford due to the police-led incident that was reported at about 7.15pm, according to National Highways East  

A statement issued by Herts Police at 7.15pm said: "Drivers are asked to avoid the M1 in the Watford and St Albans area whilst police deal with an ongoing incident.

"There is currently a closure between junction 6 and 5 northbound. Thank you for your patience."

Update on August 20: the road reopened last night after being closed for about an hour from around 7.15pm.