Modern slavery risk orders are aimed at providing protection for victims where there has been a conviction, but their creation within the act is now being reconsidered, and their enforceability put in doubt.

The act, an amendment bill and draft regulations have since been referred to a NSW upper house committee inquiry for scrutiny.

Acting anti-slavery commissioner Professor Jennifer Burn told the inquiry on Monday the state government had been informed by the Department of Public Prosecutions and Legal Aid that "significant technical and legal issues" existed around the creation of such risk orders.

The potential risk posed by modern slavery offenders could be addressed by schemes under existing legislation, Prof Burn said.

But Labor MLC Greg Donnelly said the proposed change reneged on what was expected and agreed upon when the bill was passed.

"It was the explicit intention to create these modern slavery risk orders; that was fundamental to what transpired in the parliament," Mr Donnelly told Prof Burn.

"I see this as a walking back. A proposition to repeal this very important part of the act is walking back from what the parliament intended."

There have been just 24 convictions for modern slavery across Australia since 2004.

Of more than 800 cases investigated by federal police since 2004, more than 45 per cent were NSW-based, Prof Burn said.

The NSW Parliament became the first Australian state to pass a Modern Slavery Bill in June 2018.

Greens MLC David Shoebridge said the act was passed to "toughen up the law" and establish new ways to enforce anti-slavery provisions.

He told AAP the removal of risk orders would weaken legislation and set a bad example to other countries watching the state's legal developments in this area.

"It would be a terrible precedent of actually stepping backwards on protections against modern slavery right at a time when I think the public are calling for governments to act," Mr Shoebridge said.

Australian Associated Press