Detectives hope the public can help them solve a mystery by identifying a man found unconscious in an alleyway.

The man, thought to be in his late 20s, has suffered head injuries.

Sedated and on a ventilator in hospital, he has so far been unable to tell police who he is and no clues to his identity were found in his pockets.

Police do not know if he suffered his injuries in a fall or if he is the victim of foul play.

He was discovered collapsed in an alleyway behind St Margaret's Road, Horton Grange, Bradford, at 6.30pm on Saturday.

He is a white, 5ft 10ins tall, thin, with short cropped dark hair, aged 25 to 30 years old and wearing a blue and white long sleeved check shirt, and blue Adidas track suit bottoms.

Detective Inspector Gerry O'Shea who is leading the investigation, said the man's injuries were not life-threatening and he expected to be able to interview him soon.

Meanwhile, a public appeal for information was being made.

"There could be a girlfriend or family sitting at home wondering where he is," Det Ch Insp O'Shea said.

"It's a complete mystery at the moment. We are appealing for anyone in the area in which he was found who may have witnessed any incident or accident, to come forward. Or he may simply have fallen."

A woman who lives nearby found the man and called an ambulance, which took him to Bradford Royal Infirmary before a decision was taken to transfer him to the Leeds General Infirmary for more specialised treatment.

Officers from Bradford North CID have made house-to-house inquiries in the St Margaret's Road area and undertaken a close examination of the scene where the man was found.

"The injuries the man has suffered could be consistent with a fall but could also be consistent with an assault, it's impossible to say," said Det Insp O'Shea.

He said the man had cash and a lighter still in his pockets and it was therefore unlikely he had been the victim of a robbery.

Anyone with information should contact Bradford North CID on (01274) 376259.