The Scottish Prison Service (SPS) confirmed the new figure was 8,100 as of yesterday.

It is thought that some 6,500 inmates live in overcrowded conditions and that nearly three-quarters (74 per cent) of the estate is over capacity.

SPS divisional head James Kerr told STV News: “When a prison is first built, there is an optimum number we would seek to have in that prison.

“That gives us the best balance between giving the prison the best possible chance of delivering outcomes that we require from the prison in terms of rehabilitation and citizenship, but value for money.

“Most of our prisons are abnormally high. There is an abnormal presentation of risk directly related to volume and complexity of prisons. It will become more challenging.”

Mr Kerr also said there are around 2,000 people who are being held on remand.

He added: “The raw fact is we overpopulate single cells by placing two people in a cell designed for a single person. That doesn’t change the size of the kitchen, the health centre, the education facility. All things designed to promote citizenship become harder to reach. It’s absolutely a worry.

“The bottom line is trying to squeeze more people into the same space raises anxieties and frustration. Access to services becomes more challenging as a consequence of that.”