The prison service is on the brink of crisis, with an ever-rising number of inmates and increases in the number of violent incidents and assaults, according to the Prison Reform Trust (PRT).

The report, released as part of the PRT’s annual analysis of the state of the prison system in England and Wales, reveals that stringent budget cuts, which are due to total ￡2.4bn by 2015-16, are putting the prison service under even greater pressures.

This comes at a time when nearly two-thirds of prisons are over-capacity, according to the Ministry of Justice, accommodating, on average, 2,687 more people than they were designed to. And, in the last two weeks alone, prison numbers increased by more than 500, enough to fill a small prison.

The report, titled Prison: the facts also showed that there were 10,996 recorded prisoner on prisoner assaults and 2,731 recoded prisoner on officer assaults in 2013.

Director of the Prison Reform Trust, Juliet Lyon, said: “These latest figures reveal a prison service having to cope with unprecedented strain. Ministers must heed the warning signs. Rising assault and suicide rates, fewer staff and less constructive activity, call into question the government’s commitment to safety and decency. Slashing prison budgets and introducing harsher regimes while warehousing even greater numbers overseen by fewer staff is no way to transform rehabilitation.”

Tom Jones, head of policy at Thompsons Solicitors, the firm that represents the Prisons Officers’ Association (POA) and its members, commented: “This report confirms what we have been saying and our cases have been pointing to. The government’s crippling austerity measures are having a major impact on all aspects of the prison service, something that will only serve to have a negative impact on society as a whole.

“From our work with the POA, we know that, as incidents increase, it is prison officers who bear the brunt. It is wrong that, as a result of poor prison officer to inmate ratios, prisoner officers cannot carry out their job properly, and are often forced to work in a dangerous environment.

“Yet again the government will maintain that austerity measures are not having a detrimental effect on the overall performance of a service, but that is clearly not the case. The government needs to act to avert a crisis.”