Pressure on Home Secretary John Reid over the prisons overcrowding crisis heightened today as the head of the Youth Justice Board resigned with a stinging broadside on criminal justice policy.
Professor Rod Morgan said Government targets for bringing criminals to justice were "swamping" the youth courts and children's prisons with minor offenders who were "cluttering up" the system.
Meanwhile, a Crown Court judge made clear that he would resist any pressure to avoid handing down custodial sentences to help bring down prison numbers.
Judge Richard Bray said that prison populations would continue to rise until politicians woke up to the fact that courts can no longer hand down sentences tough enough to deter criminals.
His comments came as Lord Chancellor Lord Falconer said it was "inevitable" that courts would spare some offenders from being locked up because they know the cells are full.
Figures released by the Home Office today showed that the total prison population in England and Wales edged up from 79,375 to 79,731 over the past week, bringing them perilously close to the maximum capacity of 80,114.
This was despite Mr Reid and Lord Falconer circulating a note to courts reminding them of guidelines which state that prison sentences should be reserved for the most serious, dangerous and persistent offenders.
The note came under fire after a judge in North Wales said yesterday that he bore it in mind when handing down a suspended prison sentence to a man who pleaded guilty to downloading child pornography.
Lord Falconer denied that ministers were seeking to interfere in sentencing decisions.
He told BBC Radio 4's Today programme: "The guidelines remain the basis upon which the judges sentence. If those guidelines give them a choice - custodial or non-custodial - then inevitably, the fact that the prisons are near capacity could have an effect."
But Judge Bray, sitting in Northampton, said he would not allow his sentencing decisions to be swayed by the prisons crisis.
"I am well aware that there is overcrowding in the prison and detention centres," he said.
"That is not going to prevent me from passing proper sentences in each case.
"The reason our prisons are full to overcrowding, and have been for years, is because judges can no longer pass deterrent sentences."
In an interview to be broadcast on BBC2's Newsnight tonight, Prof Morgan said the country was "standing on the brink of a prisons crisis".
Government targets for bringing offenders to justice were having the "perverse consequence" of swelling prisoner numbers and bringing relatively minor young offenders into detention.
Announcing that he would not be applying for a second three-year term in office, Prof Morgan said: "We have tonight lots of people in police cells because there is no space for them in custody and that's true for children and young people also.
"I regard a 26% increase in the number of children and young people that are being drawn into the system in the past three years as swamping."
Shadow home secretary David Davis said it was an "outrage" that ministers were putting public safety at risk by seeking to persuade judges to pass lesser sentences.
Mr Reid's note was "clearly bringing a little more pressure on judges to use prison less and as a result, of course, to put the public more at risk," he told Today.
"They shouldn't be putting pressure on the judges to stop them doing their jobs properly."
The Home Office should "use whatever capacity it can get - disused military camps, prison ships, whatever you need to do, even doubling up in prisons - in order to ensure that people are not put at risk", said Mr Davis.
Lord Falconer denied that ministers were seeking to dictate the sentences handed down by judges.
"We are not seeking to interfere with judicial independence. The judges have got to make up their minds in relation to what the guidelines are," he said.
He accepted that the question of providing prison capacity was not a problem for the judges, but for politicians.
"This is a problem," said Lord Falconer. "Each part of the system can contribute in accordance with appropriate principles to trying to solve it.
"But we are not for one moment seeking to say that this is a problem that the judges have got to solve."
Tony Blair's official spokesman today confirmed that Mr Reid retains the Prime Minister's full confidence.
And he said the PM agreed with Lord Chief Justice Lord Phillips that Mr Reid's note was no more than "a reminder of existing guidelines".