Disgraced former senior tax official Nick Petroulias gave sworn evidence to a parliamentary inquiry under a fake name, it has been alleged in State Parliament - and seven MPs sitting across the table never twigged.

The Greens are now demanding a formal inquiry into the circumstances surrounding the appearance at the inquiry into Crown land, held in August 2016.

Nick Petroulias outside the ICAC inquiry into the Awabakal Local Aborignal Land Council. Credit:Janie Barrett

Mr Petroulias' face was splashed across the country's media about eight years earlier, when he was imprisoned for corrupt conduct during his stint as assistant tax commissioner.

But in Parliament on Thursday, Greens MP David Shoebridge alleged that Mr Petroulias used the alias "Nicholas Peterson" to give sworn evidence before the upper house committee, of which Mr Shoebridge was a member.