Crown courts are “struggling” to find enough judges and lawyers to deal with the backlog of cases, the most senior judge in England and Wales has warned.

The Lord Chief Justice said these were the two “greatest constraints” facing crown courts as they try to grapple with the number of cases waiting to be heard.

His comments come as watchdogs joined forces to express their “serious concerns” that the criminal justice system continued to operate at “unacceptable levels” in England and Wales and is far from recovering after the “shock” of the coronavirus pandemic.

Speaking to the Lords Constitution Committee on Wednesday, Lord Burnett said: “The two greatest constraints we have at the moment, in disposing of cases more quickly, are first, a shortage of judicial resources, we have too few crown court judges.

“Just put very straightforwardly more and more cases are not going ahead, because either the prosecution or the defence have not been able to find an advocate to deal with the case. And so there is a systemic problem, both with judicial resource and lawyer resource that has got to be dealt with.”

The number of outstanding crown court cases has fallen to its lowest level in a year, down 513 from 58,351 in February to 57,838 in March, according to the latest provisional Ministry of Justice (MoJ) figures.

The Law Society of England and Wales said the backlog is decreasing at a “glacial pace”.

Describing the causes of the problem as “complicated and multifaceted”, Lord Burnett said he hoped this coming year to increase the number of sitting days to 105,000 which would mean “we are simply running the courts 25% hotter than we were doing three years ago.”

But he added: “We’re struggling to deploy judges, and the legal profession is struggling to deploy lawyers. So those are really big capacity issues, which we’re still grappling with.

Lord Burnett said the judiciary was working “really hard” to improve the number of cases being dealt with, particularly by “squeezing out guilty pleas earlier because that’s much better for everybody”.

He said he was keen that “money should continue to be found” to keep as many of the temporary Nightingale courts open as possible and that more retired judges were being encouraged to continue sitting in crown courts.

The retirement age for judges has just risen to 70 so “one might expect a few judges to soldier on full time beyond 70 who might otherwise not have done”, he added.

Magistrates’ courts are short “between 60 and 80 district judges” across the country because there have not been “sufficient candidates” to fill positions, Lord Burnett said.

He also warned the “dispute between the Government and the Bar” needed to be dealt with, otherwise “the numbers of criminal barristers and solicitors will continue to decline at a time when police numbers are going up.”

In April criminal barristers in England and Wales began industrial action over concerns about legal aid funding. They are refusing to carry out “return work” – stepping in and picking up court hearings and other work for colleagues whose cases are overrunning – which is described as a gesture of goodwill to prop up the justice system.

Lord Burnett said it was “vitally important I say nothing which indicates taking any sides in an … industrial dispute”, but added: “There is enormous pressure on the police and the prosecuting authority to bring more cases into the criminal courts. And that’s the question, who’s going to do them?”

A Government spokesman said: “We are increasing investment in criminal legal aid by £135 million a year – the biggest increase in a decade – to ensure professionals are better paid for the work they carry out and help free up capacity in courts.

“The number of outstanding cases in the courts is falling and we are spending nearly half a billion pounds, keeping open 30 extra court rooms and increasing magistrates’ powers to speed up justice for victims.”