The Scottish Child Abuse Inquiry was extended indefinitely last week after Lady Smith said there was “no prospect” of a final report being ready for the end of next year.
In-Care Abuse Survivors (Incas) called for more detail to be provided on why that decision was made.
And it raised concerns that the extension could allow the Scottish Government to put off a decision on financial redress for victims.
The inquiry is currently investigating more than 70 institutions including boarding schools and children’s homes run by religious organisations.
Commenting on the decision to extend the inquiry, Alan Draper, a spokesman for Incas, said: “We welcome it on the one hand because it should ensure a thorough inquiry, provided it leads to appropriate prosecutions and appropriate redress.
“But there’s a danger the Scottish Government can use the delay as a way of kicking the can down the road a bit on the issue of redress.
“That’s why we need some clarification from Lady Smith on what she’s planning to do. It’s all very well extending the inquiry, but we want to know which institutions they’re looking at, so more survivors can come forward.”
The inquiry is currently hearing evidence on institutions run by the Sisters of Nazareth and is today expected to hear from Archbishop Emeritus Mario Conti, the former bishop of Aberdeen.
In a letter to Deputy First Minister John Swinney earlier this month, Lady Smith said the inquiry was “making good progress” but would not be able to report, as planned, by late 2019.
An initial report on the inquiry’s first case study, which includes Smyllum orphanage, is expected to be published soon.
An inquiry spokeswoman said: “The inquiry’s second case study is drawing near to a close, with a third case study commencing in the autumn and further case studies will be announced in due course.
“The inquiry continues to take evidence from many survivors and other witnesses with valuable information to provide. We continue to actively encourage anyone who has relevant information to get in touch.”
Anyone wishing to contact the inquiry should call 0800 0929300 or email [email protected]