POLICE say driver error has to be the cause of yet another multi-vehicle accident on the M4, the day after a smash involving nine cars.

Yesterday (Thursday) about 11am seven cars were involved in an accident at junction 17 of the motorway, with two people taken to Frenchay Hospital with what are believed to be non life-threatening injuries.

The accident happened 200 metres from the junction, on the westbound carriageway, just prior to Leigh Delamere services and lanes two and three of the motorway were blocked until 2pm.

On Wednesday nine cars were involved in a pile-up on the eastbound carriageway towards London, just after junction 15, in foggy conditions at 7.20am.

Sergeant Mark Levitt, of Swindon traffic police, said: "On Wednesday there was a crash involving nine vehicles.

"Yesterday was a bright and sunny day and there was absolutely no reason for this to happen other than drivers are not paying attention to keeping enough distance to drivers in front of them."