Asking prison governors to slash the cost of holding inmates by a further £149m in the next year can be achieved without compromising safety or rehabilitation, according to the Government.

Speaking to the Epsom Guardian last month, Ian Bickers, the governor of High Down prison, on the border of Banstead and Sutton, admitted that major cost-cutting measures introduced by the Ministry of Justice (MoJ) last year had caused operational difficulties.

The Epsom Guardian was contacted by a number of relatives of prisoners and ex-prison officers who raised concerns about staff shortages and prisoners being kept locked in their cells for long periods of time - both of which were refuted by the MoJ.

And a report by the Independent Monitoring Board (IMB) on High Down for 2013 - covering the period when cost-cutting measures were introduced - said it had been a "dreadful" year for the prison and asked the Government to consider the effect of its cost-cutting on rehabilitation.

But Michael Spurr, chief executive, of NOMS (National Offender Management Service), has announced more cuts are on the way - something the prison service claims can be achieved without cutting any services.

Savings of £149m have been identified from the cost of running prisons in 2014 to 2015 - approximately £2,200 per prisoner per year.

A prison service spokesman said: "We are making prisons more effective and cheaper to run - not by cutting services or reducing quality but by fundamentally changing the way we operate.

"We have replaced old, inefficient buildings with newer ones that are cheaper to run and ensured prison officers are in frontline roles.

"At the same time we have seen significant improvements in operational performance.

"The cost of running our prisons is too high and has to be reduced.  We can do this by being more innovative and efficient and without compromising public safety."

The spokesman denied national media reports that Justice Secretary Chris Grayling is planning to benchmark public sector prisons against the private model used at Oakwood prison to drive down costs.

But he said bench-marking is an important tool in driving efficiency: "Bench-marking is a public sector initiative and is about fundamentally changing the way we operate."