New Zealand First's shaken up its responsibilities - with leader Winston Peters handing away several portfolios.

He's passed state-owned enterprises over to controversial MP Richard Prosser, and Maori Affairs and Treaty issues to returning political veteran Pita Paraone.

Mr Peters remains in charge of his pet portfolios, including finance, immigration, foreign affairs and senior citizens.

Seasoned MP Ron Mark picks up defence and police, while the party's first-term MPs each have at least one big portfolio, including trade, social policy, corrections and internal affairs.