— Update at 2.15pm: Police were called to the Portland Street area of Lincoln at 5.55am by ambulance crews who were treating a man for a suspected stab injury.
The man died a short time later and his death is being treated as suspicious. A post mortem examination will take place later.
The age of the man has not yet been confirmed.
Police have issued a witness appeal for anyone who was in the area between Portland Street and Great Northern Terrace leading to Witham Park behind the Lincs FM building prior to 6am this morning and who may have seen anything they considered suspicious or unusual.
Portland Street remains cordoned off down to the Cross Street junction and Kesteven Street.
— First report at 10.26am: Lincolnshire Police are investigating an unexplained death in Lincoln on Saturday morning, which is affecting parts of the city.
Portland Street is closed down to Cross Street junction and Kesteven Street from Portland Street round to Clifton Street.
Other areas affected include Walnut Place and the area at the rear of the Lincs FM building at Witham Park.