Levels of risk in the prison system are increasing, the Chief Inspector of Prisons warned today.

Reductions in staff are having an impact, Nick Hardwick told MPs.

“Even in a prison that is generally performing well, there are increased levels of risk,” he told the Public Accounts Committee.

Last year there was an increase in adverse incidents such as assaults and self harm, he said.

The committee is looking at the finances of the National Offender Management Service (Noms) and committee chairwoman, Margaret Hodge, has already expressed concern over how it will cope in a time of budget cuts and rising prison population.

Ms Hodge warned in September that the plans of the agency – which runs the prison and probation service – to deliver required savings remained in doubt.

The National Audit Office said then that the Government’s abandonment of plans to halve sentences for offenders who submit early guilty pleas would deny the taxpayer £130 million of potential savings and result in there being 4,000 more people in prison than expected in 2015.

The move left Noms “scrambling to find savings elsewhere”, Ms Hodge said then.

Mr Hardwick said today that safety and decency had been improving over a period of years.

But there was an inconsistency between individual prisons.

“What we found last year was that three quarters of prisons were providing good or reasonably good outcomes around purposeful activity. But a quarter weren’t, and that is a cause for concern.

“And even in a prison that is generally performing well, we think there are increased levels of risk.”

He said a prison depended on an officer going down on to the wing for a chat.

“This kind of relationship is critical to the safety of an individual prison.

“That time to stop and take the temperature is one thing that has got squeezed.

“Generally, if the place is well run, and they have the wind behind them, they get away with it, but with less staff, the resilience isn’t there, so if something is going to go wrong, it can go wrong pretty quickly.”

Another area where there was a squeeze was in offender management activities, which were sometimes replaced by wing based activities, while supply did not meet demand for programmes for sex offenders.

He said general inconsistencies between prisons often came down to leadership, while it was easier to run a modern prison than a Victorian one.

Mr Hardwick said he did not want to scaremonger, or say that prisons were about to explode.

He said the result of a badly run prison could be apathy, rather than anger.

Liz Calderbank, Chief Inspector of Probation, said the work of probation trusts was often not fully understood or properly valued – “the contribution they make to reducing offending and managing the risk of harm that people pose to their communities”.

She added: “What we are seeing now is a proliferation of sentences, and electronic monitoring being used as a punishment rather than a mechanism of changing behaviour.

“While punishment can be effective in changing behaviour, it always needs to be affordable, and it needs to be effective in reducing reoffending, and at the moment we have no evidence, with the way that electronic monitoring is being used, that that is the case.”

Noms chief executive Michael Spurr said the prison population had been “reasonably stable” in the last 12 months, with an increase of 0.8%.

“There’s 86,000 in prison, 0.8% up on last year, but we’ve got 91,000 places available. We would have had 93,500, but we’ve been able to make some savings. I believe there is still capacity to make some more savings and still accommodate all the prisoners coming through the courts, and our projections indicate that is the case.”

He accepted that there was overcrowding in prisons but the current levels of crowding could not be reduced while still achieving savings, though he wished it was possible.

“We will have to continue at that level of crowding in order to make the financial savings we have to make,” he said.