POLICE investigating a sex assault have found a "crucial" new witness and hope to issue an artist's impression of the attacker soon.

The woman, in her 50s, was walking through Priestly Clough, a parkland area off Royds Avenue, Accrington at 6.30pm on May 24 when her attacker approached her from behind and punched her to the ground.

He then indecently assaulted her before running off.

The woman was discovered 10 hours later by a passer-by who heard her cries for help.

She was taken to Blackburn Royal Infirmary where she was treated for shock and hypothermia.

Detective Bob Eastwood is leading the investigation and said today that publicity of the incident in the Lancashire Evening Telegraph had resulted in this new witness coming forward. He said: "We have now located a crucial witness who will enable us to make further enquiries." He added that the police hope to have an artist impression of the attacker soon which will be made public in the hope that somebody recognises the attacker.

He is described as white, of mixed race or continental appearance and about 40 years old, 5ft 6in-8in tall, with medium brown hair, with a clean shaven face, small eyes, and a big nose.

He was wearing a long sleeved waterproof bomber jacket that was zipped to the neck, with light blue jeans faded to the knee.

Insp Eastwood said: "My advice to females walking alone through open spaces is to be very much on their guard."

Anyone with information on the assault is urged to contact Accrington police on 01254 353742.