Twenty cars were spotted lining up with punctures after they hit a pothole on a busy stretch of the M4, a motorist has said.

They are one of three motorists affected by the issue on Tuesday evening near Heathrow Airport.

They reported seeing a lane closure sign and "20 cars all lined up with flat tyres" on the M4 near the airport in the evening.

On the stretch between, Junctions 4 and 4B, dozens of vehicles had reportedly hit a pothole and were left stranded on the smart motorway.

One passenger said she was in the car heading westbound when she encountered a pothole on the M4 westbound just after Junction 4B.

"We were returning from Gatwick and there was a horrific bang as my daughter drove through a massive pothole.

"We pulled to the side of the motorway in the dark and went to join many other cars, most of which had sustained flat tyres."

The family were left "extremely shaken".

At around 8.30pm another motorist said they encountered the pothole but their tyres survived.

They reported seeing 15 cars on the verge and no police or highway patrol present.

"The refuge lay-by was full with four cars and we nearly hit a car stationary in the left-hand lane.

"There was a 50-mile-an-hour warning but no lane closure at that time. Horrendous, very relieved to get home safely."

Highways England has been approached for comment.