Residents have been warned to be on their guard after a driver had his top-of-the-range car stolen in an Internet scam.

The 55-year-old man fell victim to the con after advertising his Audi RS4 for sale on a local free listings website Gumtree.

But when a prospective buyer showed interest in the car the unsuspecting seller was assaulted and his car was driven off in front of him.

Police say the victim was pushed to the ground moments after he had accompanied the “buyer” who called himself “Lewi” on a test drive near to his Hedge End home.

When they returned to Mallow Road the man was knocked to the ground by the car thief, who then drove off in the £13,000 vehicle.

Officers say the car – with registration number YK51 BBF – is yet to be traced. They are appealing for help in finding the man responsible, who is thought to be around 30 years old.

He was of Indian Asian appearance, around 5ft 7in, with short, black, straight hair, clean shaven and with pock marks on the left-hand side of his face.

The victim told police the thief was wearing blue jeans and a North Face-type, dark, lightweight, waterproof jacket.

DC Maryann Attard-Charrett said they were actively following “a number of lines” of inquiry to find the car and the thief.

But today Hampshire residents are being warned to stay vigilant and take simple steps to protect themselves when selling online and selling vehicles in person.

PC Simon Wright, of Hampshire Crimestoppers, said: “If you are selling your vehicle, never let the potential purchaser have the keys unless you are also in the vehicle.

“If you drive first on a test drive take the keys out of the ignition until everyone is back in the car and then pass them over.”

He also advised sellers and buyers to avoid meeting in a car park or somewhere isolated and to try to meet at either the seller or buyer’s home for safety and so you have a link to the person.

He added not to release the car until a legitimate payment had been received.

Consumer watchdog Trading added: “We would advise people to be careful when buying or selling online. People need to be aware of their own safety,” adding that anyone who had concerns about an online seller to call the Citizens Advice Bureau on 0345 4040506 or visit actionfraud.police.uk.

Police are asking anyone who recognises the description of the suspect or has information about what happened on Sunday, January 11 to call 101 or Crimestoppers anonymously on 0800 555 111.

Nobody from the Gumtree site was available for comment.