Police have appealed for witnesses after a suspected hit-and-run left a man dead on the M1 near Watford.

The man's body was found by officers close to the hard shoulder of the northbound carriageway, between junctions 4 and 5, at around 2.30pm yesterday (December 4).

It is suspected that the man, who is from London and in his 40s, was struck by the vehicle sometime between 4.30am on Sunday, December 3, and 2.30pm the following day.

Herts Police said several cars stopped when the collision happened and officers are "particularly keen to hear from the driver of a white Mercedes".

The road was closed whilst investigations took place and it was reopened at around 8.30pm the same day.

Detective Inspector Garry Webb, from the Bedfordshire, Cambridgeshire and Hertfordshire Road Policing Unit, said: “Our thoughts are with the man’s family at this terrible time. Specially trained officers are supporting their family.

“We want to hear from anybody who saw what happened or has information that can help. If you were driving along the M1 and have a dash cam, please check it and get in touch if you spot something that might help our investigation.

“We believe a number of cars stopped when the collision occurred and we are particularly keen to hear from the driver of a white Mercedes."

He added: “Finally, I would like to thank the public for their patience whilst we carried out investigations at the scene yesterday. We appreciate the road closure would have caused disruption."

Paul Ridley, who was on a coach bound for Shropshire, reported being stationary north of junction 4 for more than two hours.

He said at the time: "We’re about 100 yards from the police stoppage. We were pulled to a halt at 3.10pm.

"In situations like this you can only feel for those involved and we wait patiently."

For several hours, traffic was diverted north via the A406, A41 and A1.

Information can be reported by emailing SCIUSouth@bch.police.uk quoting Op Byron, or by calling non-emergency number 101.