In Merseyside – where riots first erupted – there were rumoured to be just two spaces left in the prison system at the weekend

Far-right riots have pushed Britain’s prisons to breaking point as the government triggers emergency measures to ease overcrowding.

Experts fear hard-won capacity gained by releasing prisoners early has “rapidly evaporated” after at least 677 suspected rioters were charged following widespread disorder.

In Merseyside – where clashes first erupted following the killing of three schoolgirls last month – there were rumoured to be just two prison spaces left at the weekend after rioters were hauled before the courts in fast-tracked hearings.

It is the latest crisis to hit the creaking criminal justice system.

Stuart Nolan, chair of the criminal law committee at the Law Society, said the riots were the “straw that broke the camel’s back”.

“When you have got a chronic situation all you need is an acute issue and the whole thing starts to be a little bit troubling,” he told The Independent.

At least 460 people had appeared in magistrates’ courts in relation to the disorder by late last week.

Nationwide, there were only 340 places left in the male estate after 397 new receptions, chair of the Prison Officers’ Association, Mark Fairhurst, said.

Operation Early Dawn, triggered on Monday in parts of the north including Merseyside, has been described as a “one in, one out” policy which will see defendants held in police cells and not summoned to magistrates’ court until a space in prison is available.

It is feared the move could see suspects released on police bail if prison spaces cannot be found, although ministers insist no one who poses a risk to the public will be freed.

The prime minister admitted his government was making “difficult decisions” as weeks of violent disorder have placed “additional strain” on the overloaded prison system they inherited from the Tories.

Downing Street said the plans, in place in North East and Yorkshire; Cumbria and Lancashire; and Manchester, Merseyside and Cheshire regions, could be triggered and deactivated several times over the next few weeks.

Asked if the emergency measures posed a risk to public safety during a visit to Belfast, Sir Keir Starmer said the government was making “really tough decisions, and nobody wants to take them” due to a “basic failure” by the previous Conservative administration to have enough prison places available.

Longer term measures announced to ease overcrowding, which will see some prisoners serve just 40 per cent of their sentence in jail, are not due to come into force until 10 September.

The SDS40 scheme – which does not apply to those convicted of sex offences, terrorism, domestic abuse or some violent offences – is expected to result in 5,500 offenders being released in September and October.

The Prison Reform Trust (PRT) warned Operation Early Dawn may need to be expanded – along with further possible measures – to ease pressures in the coming months after the influx of hundreds of rioters swallowed up any breathing space in the prison estate.

It comes after months of warnings from criminal justice leaders, reported by The Independent, that the prison system is at breaking point.

Alex Hewson, interim head of policy and communications at the PRT, said: “I think this is a worrying time because the space the government thought it had unlocked by introducing SDS40 has rapidly evaporated. I think it will be a difficult few months whilst they try to work through this.

“It just shows how little resilience there is in the system.”

Mr Nolan said emergency measures announced under Operation Early Dawn are designed to help ease the short-term pressure, but will not address the long-term problem.

“What it hopes to do is provide a pressure cooker release for critical points,” he added. “But it doesn’t deal with the problem. It doesn’t fix the problem. It just displaces it and buys some time.”

Andrew Neilson, of the Howard League for Penal Reform, said the emergency measures were “concerning” but would help to see the prison estate through until automatic early release measures come into force.

“I think clearly there will be decisions that need to be made on a daily basis which is part of what Early Dawn is doing,” he said.

“They are a means for the government to manage over the next few weeks.

“It’s literally managing the day-to-day pressures between the courts, police custody and prison.”

Meanwhile, the Magistrates’ Association said they are “very concerned” about delayed hearings exacerbating court backlogs.

Chief executive Tom Franklin said they had been assured pressures will ease when the SDS40 scheme comes into force.

“Every case that is delayed has real-life consequences for victims, witnesses and defendants – and leads to magistrates and court staff sitting around waiting, rather than administering justice,” he said. “That is a waste of resources, at a time when there are already large backlogs.

“This emergency measure – while it is necessary – also demonstrates the parlous state of the criminal justice system and the need for an injection of more resources at every stage of the justice process.”

National Police Chiefs’ Council custody lead, Deputy Chief Constable Nev Kemp, said: “Policing will continue to arrest anyone that they need to in order to keep the public safe, including policing protests and events and ensuring that people are arrested as expected.”

Operation Early Dawn was previously triggered by the Conservative government in May in a bid to tackle overcrowding in jails.