New Zealand's prime minister, Jacinda Ardern. [Source: RNZ]

New Zealand’s prime minister says her government will do what it can to encourage Micronesian countries to stay in the Pacific Island Forum.

Nauru, Kiribati, Marshall Islands, Palau and the Federated States of Micronesia decided to withdraw from the Forum.

Micronesia’s leaders are upset over the appointment of former Cook Islands prime Minister Henry Puna as the Forum’s new secretary-general

They say South Pacific countries dishonoured a “gentleman’s agreement” under which it was Micronesia’s turn.

Jacinda Ardern said the Micronesian leaders’ decision was regrettable and saddening.