Barristers have accused ministers of ignoring a crisis in the criminal justice system by continuing to roll out pre-recorded video evidence for rape survivors in England and Wales amid a strike by advocates.

The policy, allowing complainants of offences including modern slavery to be cross-examined before trial in front of a limited number of people, was extended to five more crown courts on Friday, taking the total to 63. Three-quarters of courts are covered and all will be by the end of the month.

While barristers support the thinking behind section 28, which also covers witnesses, they say there are insufficient resources and funding for it, particularly in the light of the indefinite walkout over legal aid fees, which began on Monday.

The Criminal Bar Association said even before the strike had begun some advocates refused to do section 28 cases because of the amount of extra work it entailed for no additional money.

Kirsty Brimelow, the CBA chair, said: “It’s introducing processes while having fingers in your ears and your eyes shut as to the practical reality of how justice is being delivered in the criminal courts. You can’t keep introducing extra processes with extra work for barristers without proper funding.

“The case itself might be listed in a year’s time. The barrister then has to prepare the case again when it comes to trial for no extra money.”

Before recording the evidence barristers have to attend a “ground rules” hearing and must submit questions for the complainant. Section 28 interviews take precedent over other matters, even if the advocate is in the middle of another trial, which may have to be suspended as a result.

Mary Aspinall-Miles, who sits on the CBA’s rape and serious sexual offences group, said: “Nobody wants to traumatise complainants or defendants any more than they need to be, that’s why we support section 28 in principle, she said. “But the Ministry of Justice [MoJ] and lord chancellor have tried to act as if it’s business as usual while ignoring an increasing backlog [in the courts].

“It’s not taking the bigger picture into account. What’s this actually going to do to crown court listings? How is this going to work in practice? How are the resources going to be made available to court judges to be able to run this efficiently and effectively? And how is it going to interplay with availability?”

On Thursday, the CBA said the new justice secretary, Brandon Lewis, had agreed to meet its leaders after they had been angered by the refusal of his predecessor, Dominic Raab, to face them over the negotiating table.

Criminal barristers are demanding a 25% increase in legal aid fees after a fall in their real earnings of 28% since 2006. They say such a rise is required to prevent the collapse of a criminal justice system on its knees because of cuts. The government has agreed to a 15% uplift but only to new cases and the CBA says the crown courts’ backlog of about 60,000 cases means the increase could take years to have effect.

James Oliveira-Agnew, a barrister who helps run vulnerable witness training for other advocates. said of section 28: “It’s a good idea but just as with everything that seems to go through criminal justice, it’s a good idea poorly thought out. It needs funding, and it needs people to be paid property for it. Otherwise, it’s just not going to work.”

The MoJ did not comment on the criticisms but the justice minister, Rachel Maclean, said pre-recorded evidence was a vital part of “overhauling the way rape victims are supported through the criminal justice system so that more cases come to court and more rapists are put safely behind bars”.