A prisoner is being treated by medical staff after a fire broke out in his cell.
Fire and ambulance crews were called to HMP Winchester following a report of a blaze in a cell on B wing.
South Central Ambulance Service said: “We had a call from the fire service at 3.02pm about a fire in a prison cell.
“We sent our hazardous area response team (HART) and four vehicles along with an ambulance officer and a rapid response vehicle.
“The prisoner was taken out of the cell and is being cared for by the prison’s health care team.”
A Ministry of Justice spokeswoman confirmed there had been a “small fire in a single prison cell”.
Hampshire Fire and Rescue Service said it sent three appliances but they were not required and left the scene.
A Prison Service spokeswoman said: “Staff at HMP Winchester put out a small cell fire on Thursday 5 January. There were no injuries to staff or prisoners and the fire service attended as a precaution.”