Former National Party cabinet minister Simon Upton says he is "acutely conscious" of the need to be independent in his new job of parliamentary commissioner for the environment.

Mr Upton, who now works for the OECD in Paris, is set to take over from Jan Wright when her second five-year term ends in October.

But NZ First launched a scathing broadside of Mr Upton's appointment, saying it should be an independent role and pointing out the previous commissioners were qualified scientists while Mr Upton had degrees in English literature, music, law and a masters in political philosophy.

"How can we accept a re-tread who's been a National Party Member of Parliament for 19 years, a cabinet minister who in the pantheon of cabinet ministers, is right up there with Dr Nick Smith," deputy leader Ron Mark said on Thursday.

"What we need as the next Parliamentary Commissioner for the Environment is not a previous Young Nationals chairman.

"This sets a terrible precedent for a role that demands an authoritative respected voice."

But Mr Upton, in a statement, said he was aware of the needs of the role.

"I am acutely conscious that the office requires a scrupulously independent treatment of environmental issues and must be able to command the confidence of the House and the wider public."

"While it is not the job of the Commissioner to campaign for particular policy options, he or she can definitely assist the decision-making and legislative process by ensuring that it is well-informed."

Mr Upton was an MP for 20 years before leaving parliament in 2001, and held several cabinet positions including health minister and minister for the environment.