A distinctive tobacco tin left at the scene of a "harrowing" sex assault on an 87-year-old Alzheimer's sufferer could lead police to the attacker.

Detectives believe the suspect may have left it in his hurry to flee the scene in the early hours of Thursday.

The victim's son returned from a night out and disturbed a semi-naked man in the house in South Shore, Blackpool.

Lancashire Police believe the tin does not belong to anyone inside the house - or any legitimate visitor.

Det Ch Insp Neil Esseen, leading the investigation, said: "The tin is distinctive so I am hoping that someone may recognise it and tell us who it belongs to.

"This was a particularly sickening and harrowing attack on a vulnerable elderly woman in her home.

"We are making further enquiries about the origin of this tobacco tin and it may be that we are able to trace the owner ourselves, but this could take some time.

'Partially naked'

"I am sure the public would want to help me catch this man so I would urge anyone with any information to contact me as soon as possible."

The elderly victim was found in the living room of her home with her clothes disturbed, although she was not physically injured.

The offender is described as a white man of medium build, short dark hair and about 5ft 6ins tall.

He was aged in his late 30s to early 40s, had a Scottish accent and was partially naked when he fled the house.

Officers believe the man behind the attack was a heavy smoker.