The UK Border Agency has confirmed the demonstrator on the roof of the Morton Hall centre in Swinderby near Lincoln is a detainee of the immigration centre.
"There is currently a peaceful protest ongoing at Morton Hall in which one detainee has scaled the roof.
"We are working with the Prison Service to resolve the situation."
More top news
West Midlands weather: Wet and breezy
East Midlands Weather: Cloudy start to the day with outbreaks of rain
A large tent has been put up around the area while investigations continue.