Child abuse survivors' groups have said they have "no trust left" in Scotland's Child Abuse Inquiry.
White Flowers Alba and In Care Abuse Survivors Group both called for urgent answers from the Scottish government on the future of the inquiry.
The probe has been plagued by problems and all three original panel members have now resigned.
Deputy First Minister John Swinney said he understood the concerns but told the BBC the inquiry was gathering momentum.
Glen Houston resigned from the panel on Tuesday. He said his new appointments to the boards of two public sector organisations meant there was potentially a conflict of interest with his work on the abuse inquiry.
The other two original panel members, Susan O'Brien QC and Prof Michael Lamb, stood down within days of each other last year, complaining of government interference.
In July 2016, senior judge Lady Smith was appointed as the new chairwoman following Ms O'Brien's resignation.
The spokesman for the survivors' group White Flowers Alba, Andi Lavery, claimed there were fewer than 200 survivors now in contact with the inquiry and said there was "no trust left".
"It's an absolute disgrace and it's so terribly sad. I don't know anybody that's left that wants to testify and we're in contact with quite a number of survivors," he told BBC Radio's Good Morning Scotland programme.
"At the end of the day, if you're abused in Scotland you face no prospect of either justice, accountability or redress. But if you're abused in Carlisle or Belfast, you face them in their inquiries.
"That's not right, it's not equality and it's not justice."
The inquiry was launched in October 2015 and charged with examining historical allegations of child abuse in residential accommodation in Scotland.
It is due to report in 2019.
Also speaking on BBC Radio Scotland, Alan Draper, of the In Care Abuse Survivors Group, said survivors were concerned about the resignation of Mr Houston and the Scottish government's decision not to replace him on the panel.
"It looks too legalistic to us. All we've got now is a High Court judge, QCs and solicitors involved in the inquiry team and no external expertise. This looks far too narrow," Mr Draper said.
Failed in care
The group have also demanded that Mr Swinney tell them why the inquiry will not consider redress for victims.
Mr Draper told BBC Scotland: "We've continued to ask John Swinney that this be part of the remit. We've been denied this remit.
"What survivors tend to feel [is that] we were failed when we were in care. We continue to be failed by the Scottish government and we continue to be failed by the inquiry - why should we engage with it?"
But Mr Swinney insisted the inquiry had a "very broad remit" and would ensure justice was delivered to abuse survivors.
He also defended the decision not to appoint a successor to Mr Houston, saying that survivors' groups had told him "very strongly" they wanted the inquiry to be led by a senior judge.
The deputy first minister told the BBC that Lady Smith also had the ability to appoint assessors to "enhance the expertise of the inquiry".
"I completely understand the concern of survivors and I've engaged with survivors on a number of occasions since I took over responsibility of the Child Abuse Inquiry and I will continue to do so," he said.
"The inquiry is gathering evidence, it's gathering momentum, it's gathering input from individuals who were the victims of abuse.
"So the inquiry in that respect is doing exactly what it was commissioned to do which is to pursue justice and accountability for the survivors of abuse.
"On the question of redress, I acknowledge this to be a significant issue, but it's an issue for the government to address in consultation with the survivors. It's not for me to pass this to the inquiry."