A teenage girl was punched to the ground and beaten as she lay helpless.

The 16-year-old victim, who was walking her dog, was left with bruising and swelling on her face after the attack in Livingston on Tuesday.

Police have vowed to find the person responsible, who is thought to be in his late teens.

The victim was walking on a footpath to the rear of houses at Wester Bankton in Murieston when the suspect approached her around 6.30pm.

She was punched to the ground and the attacker continued to strike her as she lay there.

He then ran off towards Murieston East Road.

The suspect is described as white and in his late teens, about 5ft 7in and of stocky build. He has freckles across his cheeks and nose, dark blue eyes and ginger hair.

He was wearing a grey Adidas tracksuit with blue stripes down the arms and legs, a dark grey roundneck T-shirt and black Nike canvas trainers.

Inspector Adam Smith, of Livingston Police Station, said: "We are very concerned about this unprovoked assault which has left the young victim extremely shaken and distressed.

"We are committed to finding the person responsible and I would urge anyone who may have witnessed anything or has any information which can help with our enquiries to get in touch."

Anyone with information has been asked to call police on 101 or Crimestoppers on 0800 555 111.