DETECTIVES are anxious to trace a key witness in the hunt for a rapist who stripped and attacked a teenager in Farnworth's Moses Gate Country Park.

The witness, in his 50s with grey hair, was walking close to the cemetery at 2.20pm on Tuesday after the 17-year-old girl was attacked.

Police believe he may have vital information which can help them to track down the wanted man.

Mounted police officers have been drafted in to search the secluded park and surrounding land.

Detectives have also set up a mobile police station in the Rock Hall Visitors Centre car park.

Officers were today talking to dog walkers and passers-by in a bid to trace people who were in the park on Tuesday between noon and 4pm. The victim is still being interviewed by police.

The teenager was grabbed as she walked her dog in the park at approximately 2pm. She ran naked and screaming from the scene. Detectives believe the man they are looking for was a stranger to the victim.

Det Insp Andy Aston today said: "We have a dedicated team of detectives working on this case, and over the next few days we will have teams of extra officers in the park speaking to members of the public.

"I am appealing to people who may have been in the area around the park on Tuesday afternoon to contact officers.

"They may be able to provide us with vital information to help us catch this man.

"We are particularly keen to speak to the man in his 50s, who was seen walking close to the cemetery at around 2.20pm on Tuesday. I must stress this man is not a suspect."

Women are being warned to be on their guard while the rapist is on the loose.

So far police have combed the grassland and paths with search dogs. A forensic team has also examined the scene.

Much of the picturesque park was sealed off. The Rock Hall Information Centre was also deemed out of bounds during the forensic investigation.

Anyone who has any information is asked to contact the CID at Farnworth on 0161 856 5853 or contact Crimestoppers anonymously on 0800 555 111.