An internal investigation is under way at HMP Northumberland after an inmate assaulted a prison officer at the weekend.
The incident happened on Saturday at the Acklington-based category C unit, which is run by Sodexo Justice Services.
A spokesman for the company would not elaborate on the incident, but confirmed: "A prison officer was assaulted during an incident at HMP Northumberland on Saturday; he did not require medical attention."
The incident came a day after an inmate at the prison escaped from hospital on a motorbike before being tracked down and recaptured.
Police were called to the new hospital in Cramlington at 6pm on Friday after receiving reports that a prisoner from the unit, who had attended the hospital, had escaped.
The prisoner, a 36-year-old man who had received treatment and was with prison staff, was leaving the hospital when he ran off. He subsequently escaped on a motorbike which he had stolen.
Police officers carried out a search and located the motorbike and the escaped prisoner at an address in Wallsend two hours later.
One man, aged 36, has been arrested on suspicion of escaping from lawful custody, two others, a man aged 27 and a woman aged 25, have both been arrested on suspicion of assisting an escapee. Inquiries are continuing into the incident.
A Sodexo spokesman said: "We can confirm that a prisoner from HMP Northumberland escaped custody on Friday evening on the way back to the prison from outside the hospital.
“The police were called immediately and the prisoner was apprehended and arrested and is now in police custody. A full investigation will be carried out into this incident."