Disability Advocacy Network Australia chief executive Mary Mallett said some support groups have been scrambling to support people wanting to make a submission to the inquiry and those appearing at public hearings.

"Some of them are already inundated with the number of people who need help to write a submission," Ms Mallett told AAP as counselling and advocacy providers met in Melbourne on Friday.

"Some of these people have years of information, stories and frustrations and all of the experiences that they or their family member have had."

Ms Mallett said there were concerns about the confidentiality of information provided to the inquiry, given people with disabilities and their families often did not complain out of fear of retribution.

"That same sense of being afraid to complain is exactly the same constraint that will stop people coming forward to the royal commission because they think their situation will get worse if they put their head up about the parapet and say, 'This isn't good, I shouldn't have to put up with this'."

Inclusion Australia CEO Catherine McAlpine said it was particularly a problem for people who live in regional and remote areas or in group homes.

"If they complain about that provider, they've got nowhere else to go," Ms McAlpine said.

The royal commission's website said it took concerns about retribution very seriously because it can be a criminal offence.

Ms McAlpine said the group most likely to have experienced violence, abuse, neglect and exploitation were people with intellectual disability who had very limited ability to represent themselves or say what happened.

"The challenge for the royal commission is to make sure that those stories are told in a way that keeps people safe but to make sure that those stories are told."

Children and Young People with Disability CEO Mary Sayers said the group would have preferred a longer lead time to help people safely tell their story and believed the rollout of legal assistance needed to be accelerated.

Social Services Minister Anne Ruston said almost $140 million was being invested in advocacy, counselling and legal assistance services to support people engaging with the royal commission over the next three years.

The royal commission will hold a public hearing in Melbourne next week focusing on group homes offering supported accommodation for up to six people with disabilities.

Chair Ronald Sackville QC said advocacy organisations have argued group homes provide an environment in which violence, abuse, neglect or exploitation are apt to take place and the commission intended to assess the force of that argument.

Australian Associated Press