The NSW coalition has defended shifting position on the voice to parliament, saying the former Perrottet government's decision to support the proposal was only ever "in principle".

Opposition Leader Mark Speakman said last week all NSW Liberal National coalition MPs would be free to campaign either for or against the Indigenous voice to parliament referendum.

It signals a shift from former Liberal premier Dominic Perrottet's support for the voice.

Mr Perrottet had urged leaders to adopt a united stance on the advisory body.

"We don't need division, we need unity," he said in January.

After the coalition lost the March election, the federal Liberal Party formalised its negative position on the voice.

Mr Speakman said the NSW coalition shift was not a reversal.

"Premier Perrottet supported a voice to parliament, in principle ... the circumstances have changed since ," he told Sky News on Tuesday.

While sympathetic to the idea of Aboriginal and Torres Strait Islander people having a voice to parliament, Mr Speakman said he remained concerned about the wording.

"What we now have is a proposal for a voice to the executive as well."

A cross parliamentary committee report released on Friday said the need for Aboriginal and Torres Strait Islander people to be recognised in the constitution was "unquestionable".

"The committee has only one recommendation: the passage of the constitution alteration, unamended," the report said.

Mr Speakman said he had not had time to digest the report, but wanted to scrutinise it closely, including the dissenting statements.

"There is a dissenting report by the parliamentary committee and I want to look at that in detail before I can comment."