Victims of state abuse are in shock after news a convicted paedophile attended Royal Commission of Inquiry gatherings with sexual abuse survivors.

State abuse survivors on the Survivor Advisory Group, Tyrone Marks and Cath Coster, have been left reeling.

"I was subjected to paedophiles by being a ward of the state; to be standing up now to get the truth out of the state, I would not have expected to be put in this position," Coster told Newshub.

Coster said she has unwittingly been at two informal meetings with the offender, and said she had even spoken with him directly.

"To find out later on that I had put myself into a situation where there was a paedophile, it made me feel real sick."

Marks expressed concern about the direction of the commission, telling Newshub: "We feel this commission is heading in a downward spiral."

The sex offender's partner is also a member of the commission's Survivor Advisory Group, and neither of them can be identified for legal reasons.

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The commission knew in May the man had convictions but it wasn't until August that the partner revealed he had sexual offence convictions.

Survivor Advisory Group sponsoring Commissioner Paul Gibson has apologised over the revelations and admits it would have been difficult for victims.

"This would be traumatising; it is traumatising for people, especially if they've experienced that kind of abuse."

He acknowledged the "mistake and our sorry-ness that this has happened".

The inquiry was set up to hear from people who were abused in state care. It was later expanded to include religious institutions.

Because it's a Royal Commission of Inquiry it operates largely independent of the minister in charge, Internal Affairs Minister Tracey Martin.

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But she said she is not happy with the Commission.

"I want to see what my powers are around concerning what looks to me like concerning decision-making," the minister said.

In the House on Tuesday, Martin said she asked survivors who may be deterred from taking part to make sure they articulate their concerns directly to the inquiry.

"They have the right to demand better, and I ask them to go and do that."

The real damage that's been done is to the people the inquiry was set up for: the survivors of abuse.

The commission must now do all it can to reassure victims they are safe to tell their stories.