The motorway remained closed on Sunday afternoon between junctions 22 (London Colney) and 21A (North Orbital Road/St Albans) after the incident at around 4am.

Officers had pursued a van before it was involved in a collision with three other vehicles.

No police cars were involved in the crash and the chase had been stood down before the incident.

No indication has been given by Hertfordshire Constabulary of which vehicle the woman was in.

The force said in a statement said: "A woman has sadly passed away and her family are being supported by specially trained officers."

It added: "As a matter of course, the incident has been referred to the Independent Office for Police Conduct."