Two prison officers needed hospital treatment following a riot in a West Lothian prison.

The emergency services were called to HMP Addiewell on Monday night after trouble flared among inmates.

The Scottish Ambulance Service said a 29-year-old man was taken to Livingston's St John's hospital with head and facial injuries at around 7.50pm.

Another male officer received hospital treatment but prison officials confirmed both had since been discharged from hospital.

Lothian and Borders police said up to 10 prisoners were "actively" involved in the incident.

Private company Kalyx, which manages HMP Addiewell for the Scottish Prison Service, said: "We can confirm that a contained incident, involving a small number of prisoners, took place in one of the wings at HMP Addiewell on the evening of Monday 25th January and was brought under control last night.

"There has been minor damage caused, mainly as a result of burst pipes.

"Two prison officers were injured during the incident and were treated at hospital but have now been discharged."

Two ambulance "special operations response teams" stood by outside the jail from 8.30pm until 1am after reports of a riot in the prison.

Lothian and Borders Fire and Rescue service were also at the scene until midnight, after they were called to investigate a fire alarm at around 7.30pm.

HMP Addiewell opened in December 2008 and has places for 700 prisoners. Last October, a member of staff was taken to hospital following a disturbance.

There was also a riot there last February.

The latest riot prompted a former chief inspector of prisons in Scotland said prisoners take advantage of the fact that privately run jails have fewer staff working.

Now, a former chief inspector of prisons has spoken out, saying prisoners in private jails can take advantage of lower staffing levels.

Sir Clive Fairweather said private prisons have to make a profit, which can result in reduced staffing and training.

He said: "The difference between a privately run prison and the rest of the prison estate is that first and foremost it's innovative and really has cutting-edge systems but it comes with a bit of a problem which the governor always has to overcome, which is it's got to make a profit.

"To make a profit the only place you can cut corners is on staffing."

He said he had previously inspected another private jail in Kilmarnock, and insisted that prisoners there and in Addiewell have "never had it so good".

He said: "They didn't want to go anywhere else but they are taking advantage of the fact there aren't the same staffing levels as there are in other major prisons.

"Indeed were there to be major riots in somewhere like Addiewell or Kilmarnock, I'm pretty certain the riot shields and those to deal with it would actually have to come from the rest of the SPS."

Mr Fairweather said Government ministers needed to back the governor and staff at Addiewell and urge Kalyx to look again at the number of workers in HMP Addiewell and the level of training they receive.