A traffic policeman told how he was left clinging to the side of a car as it zig-zagged along a busy motorway at speeds of up to 80mph for half a mile.

PC Geoffrey Poyser told how he went into a "blind panic" as the car sped down the M11 near Stansted airport, Essex, in October last year.

He said at one point the driver, unemployed Joe Butler, 25, of Essex Road, Bognor, who denies attempting to murder PC Poyser, looked down at him and said: "You are going to die, you bastard."

The officer, 53 at the time of the incident, eventually rolled away as the car slowed to 30mph and was left with severe bruising and cuts to his body and legs, Chelmsford Crown Court heard.

PC Poyser and his colleague PC Lorraine Mann, who was 38, stopped Butler, who was with his girlfriend Sarah Auld, 24, from Surrey, for speeding through roadworks on the southbound carriageway at junction 8.

He said Butler punched him after being told he was being arrested on suspicion of being a disqualified driver.

Butler then drove off as PC Poyser reached through the driver's side window of the Mercedes to grab the keys. PC Poyser said he clung on to the swinging door as the car sped away.

Matthew Gowan, prosecuting, told the jury the Mercedes was found abandoned. Butler was arrested two months later.

"I was in a blind panic," PC Poyser told the court. "He looked down at me and he said: 'You are going to die, you bastard'."

The officer said he remembered Butler overtaking traffic as he sped along. Eventually the car slowed to about 30mph.

"I think he said, 'you will not stop me will you?' I replied, 'no. I won't stop you'," said PC Poyser.

"I knew I had to let go at that point. I hit the road and then I recall tumbling over and over a number of times."

PC Poyser said he stopped Butler after seeing the car travel through the 40mph roadworks speed limit at between 45mph and 60mph.

The hearing continues.