New Zealand Refining, which operates the country's only oil refinery, wants shareholders to approve a change to the company's constitution that would allow for a smaller board.

The Whangarei-based company's shareholders will vote on May 4 in Auckland on whether to back a change that would let NZ Refining cut its minimum number of directors to three from eight, and remove a maximum cap of 12 directors.

The oil refinery operator expects the board would be made up of three representatives from its oil company shareholders - ExxonMobil, BP New Zealand and Z Energy - and four independents, one of whom would be chair.

The move follows the resignation of Dean Gilbert from the board and Chevron New Zealand selling its stake, and takes into account feedback from other shareholders, NZ Refining said in its notice of annual meeting. The changes will "create the flexibility to move to a smaller number of seats on the board while continuing to safeguard minority shareholder interests," it said.


NZ Refining shareholders will also vote on re-electing independent directors Vanessa Stoddart and Mark Tume, and ExxonMobil representative Andrew Warrell.

The oil refinery benefited from the slump in international fuel prices last year, which helped widen the company's margins and underpinned a profit of $151 million for 2015.

The shares were unchanged at $3.18 and have dropped 15 percent so far this year. The stock is rated an average 'buy' based on three analyst recommendations compiled by Reuters, with a median target price of $3.65.