Concerns have been rising about a possible diplomatic row between New Zealand and the Cook Islands.

A couple of weeks ago, Foreign Minister Winston Peters publicly admonished the President of Kiribati for refusing to engage - and diplomatic aid was put under review.

Peters also recently released a harsh statement directed at Cook Islands Prime Minister Mark Brown as Brown prepares to sign a deal in China this week - a deal New Zealand hasn't been consulted about.

Massey University's Anna Powles says these incidents are 'unusual' and don't reflect the diplomatic engagement between both nations.

"It certainly doesn't reflect the type of more sensitive diplomatic engagement that we're used to New Zealand conducting in the region."

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• Govt accuses Cook Islands PM of flying to China without consulting NZ
• "Radio silence": Govt in stand-off with Kiribati, suspends financial aid