James Shaw takes the blame for confusion over Golriz Ghahraman's background

Green Party leader James Shaw is taking the blame for the confusion over new MP Golriz Ghahraman's history of defending alleged war criminals on trial.

He gave a speech in May where he said Ms Ghahraman "worked as a prosecutor at the United Nations' tribunals for Rwanda and the former Yugoslavia. She also worked on the Khmer Rouge tribunal in Cambodia".

The Iranian-born former refugee actually worked on the defence in the Rwanda and Yugoslavia trials.

"I didn't check the speech with Golriz before I gave it. Clearly I got those the wrong way around," he told NZME on Thursday.

Ms Ghahraman's background has come under heavy scrutiny this week, after a former Labour staffer took to Twitter to accuse her of being a "genocide denier" - citing her work on the defence of Joseph Nzirorera and Simon Bikindi in Rwanda. She also worked on the defence for Bosnian Serb war criminal Radovan Karadzic.

Ms Ghahraman said she has been open and honest about her work.

Profiles on Ms Ghahraman published in the New Zealand Herald and Otago Daily Times in January both said she worked as a prosecutor in Rwanda and Yugoslavia. Her profile on the Green Party website earlier this week said she worked in "Africa, The Hague and Cambodia, putting on trial world leaders for abusing their power", but has since been changed.

"It was surprising for me that there was this feeling that [my work] was hidden," Ms Ghahraman told Newshub.

"I accept that is vague, [but] I don't think it's misleading at all, because as anyone who has worked in the justice system would tell you, we're all putting on trial.

"We say, 'We're not going to sink to your level. We're not going to be tyrants. This process is going to be transparent and fair... It's very hard to work on a defence team, but it's completely necessary and it's necessary, especially if you believe in human rights."

Labour staffer Phil Quin later denied having called Ms Ghahraman a "genocide denier", then apologised once he'd realised his mistake.

Ms Ghahraman said the accusation was "offensive" and "gross".

Criticism of her work has been condemned by the Law Society.