Former Prime Minister Sir John Key has been appointed to the ANZ board.

ANZ has revealed former prime minister Sir John Key has been appointed to its New Zealand board and will become chair in January.

Current chairman John Judge is retiring.

"Sir John Key's strong international career in banking and his understanding of and contacts across the Asia-Pacific – where many Australian and New Zealand companies are increasingly trading - will add great value to the governance of ANZ," ANZ group chair David Gonski said.

Banking expert Claire Matthews, of Massey University, said it was not surprising to see Key in such a position.

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"He has a background in financial institutions and as former prime minister he has a whole lot of skills."

But she said it was surprising whenever someone was brought on to a board and put straight into the chair position, without an opportunity to serve a term as a director first to fully understand how the board operated.

She said it could be that the board wanted fresh leadership, driven by a need to change.

As a subsidiary of the ANZ operation in Australia, the role would have less influence than a standalone organisation, she said. "That's not to suggest it's not important but it's a subsidiary of a bigger organisation."

A graduate of the University of Canterbury, Key started his career in banking and finance in New Zealand before heading overseas where he became head of global foreign exchange with Merrill Lynch. He was also made a member of the Foreign Exchange Committee of the Federal Reserve Bank of New York.

Other former prime ministers have taken board positions: Jenny Shipley is chair of Genesis Energy and was on the board of Mainzeal. Jim Bolger was chair of KiwiRail.

Key is also on the board of Air New Zealand.

ANZ New Zealand's other independent directors are Tony Carter, Mark Verbiest and Joan Withers. The executive directors on the board are ANZ New Zealand chief executive David Hisco, ANZ Group chief risk officer and group executive Nigel Williams, and ANZ Group chief executive Shayne Elliott.

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