The Ministry of Justice has confirmed it is investigating an "ongoing incident" at Lincoln Prison.
A Lincoln Prison source has also confirmed there has been an "incident" at the Greetwell site.
It comes following reports of a fire breaking out this morning.
A number of fire engines and ambulances are currently outside the 140-year-old prison.
But a prison source said: "There has been a small incident. But there has been no fire and there are no injuries."
