POLICE are appealing for witnesses after a "serious" crash closed the M4 in Newport for nine hours.

The crash happened on the motorway between junctions 24 and 25 at around 7.30am on Sunday, police said.

The incident involved a white van and a green Land Rover, and both sides of the M4 were closed while the emergency services dealt with the scene.

A 67-year-old Newport man, who was driving the Land Rover, was taken to the University Hospital of Wales for treatment, and is currently in a stable condition.

The driver of the white van, a 37-year-old man from Mountain Ash, was arrested on suspicion of causing serious injury by dangerous driving.

He has since been released under investigation.

Fire crews and paramedics joined police officers in attending the incident.

Gwent Police is now appealing to the public for information that could help their investigation.

"We’re asking for anyone who was in the area around this time, or those with dashcam footage, to call us on 101 or send us a direct message on Facebook or Twitter, quoting log reference 2200221526, with any details," a spokesperson for the force said.

You can also report information to Crimestoppers anonymously by calling 0800 555 111.