A British prison is being invaded by snakes, which are scaling up the prison walls to "soak up some sun", a media report said on Saturday.
One inmate was bitten by an adder, Britain's only venomous snake. The incident has been reported from the Verne prison in southwestern England, The Australian reported.
Prison guards have posted signs warning the 600 inmates that snakes "are falling from the ramparts into the prison".
The bitten inmate said he thought the small animal approaching him was a worm, but realised it too late that it was a baby adder with its mother not far behind.
Adder bites are not fatal for adults but require immediate, painful treatment.