Southport triple killer Axel Rudakubana is being investigated by police over an alleged attack on a prison officer at HMP Belmarsh, the PA news agency understands.
The prison officer was taken to hospital as a precautionary measure after the attack on Thursday and discharged later the same evening, it is understood.
A Prison Service spokesperson said: “Police are investigating an attack on a prison officer at HMP Belmarsh yesterday.
“Violence in prison will not be tolerated and we will always push for the strongest possible punishment for attacks on our hardworking staff.”