POLICE say they are investigating the unexplained sudden death of a woman in Lincoln.

Officers were called at about 11pm on Thursday night after a passer-by found a 43-year-old lying in a passageway between the city's Portland Street and Hermit Street.

The woman, who is not believed to have lived in the flats next to where she was found, was taken to Lincoln County Hospital, but she died in the early hours of yesterday morning.

The area, between 31 and 33 Portland Street, was taped off and guarded by police while scenes of crime officers searched for forensic evidence.

And last night, a post mortem examination was under way to determine a cause of death.

Jemma Peacock, spokesman for Lincolnshire Police, said: "Police are treating the death as unexplained until the results of the post mortem indicate a cause of death and inquiries are ongoing."

Anyone with information should call Lincolnshire Police on 0300 1110300 with incident number 78 of August 27.