Driver Imran Hussain lost control when he exited the M4 motorway too late, crashing and killing his friend, a court heard.

Bristol Crown Court was told Hussain cut in front of a line of slower moving lorries before swerving off the motorway, eastbound, at the junction 17 Chippenham turn-off.

As he did so he lost control of the vehicle, slammed into a barrier and rolled down the grass verge, leaving rear seat passenger Sean Skipp with fatal injuries.

Hussain, 26, of Oxford Place, Easton, denies causing death by dangerous driving in November last year.

Robin Shellard, prosecuting, told the court Sean was living in Bristol and knew Hussain.

He said when Sean's brother Jamie asked for a lift to Bath, Sean arranged for Hussain to drive.

The court heard they set off in Hussain's black Peugeot 307, around noon, with Jamie in the front passenger seat and Sean in the back.

After travelling up the M32, they headed east on the M4, Mr Shellard said, with Jamie expecting to get off the motorway at Bath.

He said: "The car didn't get off at Bath. Mr Hussain had a sat nav and it showed a moving image and spoke to you. The sat nav told him to come off at junction 17."

The jury heard Jamie was using his mobile when they approached junction 17 and he noticed a car to their left that prevented their exit.

Mr Shellard said: "The next thing that he knew was that the Peugeot swerved to the left. They hit something like a hole in the road – the prosecution say a drain – the car span, hit the barrier and rolled down the grass verge. Unfortunately, as a result, his brother died."

The court heard traffic on the motorway came to a standstill as people stopped at the crash scene to see if they could help, and the emergency services were called.

Hussain, who was injured himself in the crash, was interviewed and told police he was an experienced driver and as he indicated to exit onto the slip road "something flashed" across the road, causing him to swerve and lose control.

Mr Shellard said it was the prosecution's case that the driver failed to react to motorway signs and left it too late to exit safely, causing him to lose control.

Lorry driver Graham Baraclough told the jury he was driving his Mercedes truck and a lorry was overtaking him, when he saw a car turn 45 degrees in front of them towards the exit.

He said: "I thought 'get ready to brake'. The back end (of the car) started to go from one side to the other and it went straight back towards the motorway, hitting the crash barrier on the slip road. At no stage did I see indicators. I saw a little bit of braking when he entered the slip road, I would imagine to get the car back under control.

"When he was on the slip road, I started slowing down. I came to a standstill and the car was on its roof."

The case continues.