DETECTIVES have launched an investigation after a 21-year-old woman was subjected to a terrifying sex attack in a town centre car park.The woman was punched in the face by her attacker as she made her way across the Rutland Arms Hotel car park in Newmarket.

DETECTIVES have launched an investigation after a 21-year-old woman was subjected to a terrifying sex attack in a town centre car park.

The woman was punched in the face by her attacker as she made her way across the Rutland Arms Hotel car park in Newmarket.

It happened at around 8pm last Thursday , but information was only released about the incident yesterday .

Police believe it was only the intervention of a Good Samaritan who shouted out at the woman's attacker which prevented the incident from turning into a far more serious assault.

The frightening attack happened close where a woman was raped in the town just over two years ago. On that occasion the 38-year-old victim was brutally attacked on the top floor of the Rookery Car Park.

Although the police are not connecting the two offences at this stage, the attacks bear a resemblance as both happened on lone woman close to their vehicles in car parks.

In the latest attack the woman had just got out of her vehicle and was walking across the hotel car park when her attacker approached her.

He asked the victim for directions and then followed her into a covered area of the car park. Detectives hunting the man say he then grabbed her.

After a struggle the attacker fell on top of the woman and he punched her in the mouth before trying to kiss her and lift her shirt.

The attacker only fled when a "Good Samaritan" shouted out as the assault was taking place. The offender stood up and left in the direction of the Waitrose store and the High Street.

Det Sgt Barry Byford, who is leading the investigation, said: "This must have been a terrifying ordeal for the young lady. She was left extremely shaken with scratches and swelling on her face, but she did not require medical treatment.

"We would like to appeal to anyone who has information relating to this offence. We are particularly keen to trace the Good Samaritan who called out and could well have prevented further injury and distress to the victim."

The offender is described as white, around 6ft 2in tall, of medium, fit build and is aged in his late 20s to early 30s.

He had a clear complexion, rosy cheeks, a large straight nose, thin lips and protruding, crossed front teeth. He was wearing black chino style trousers, a white t-shirt with dark writing on it, brown shoes with thin soles, a knitted style bobble hat and a silver metal watch.

Anyone with any information should telephone Newmarket CID on 01284 772100 or Crimestoppers on 0800 555111.