New Zealand has accused the Cook Islands government of a lack of transparency over its plans to strike a partnership deal with China.

The tiny Pacific Island nation’s leader, Mark Brown, is this week making his country’s first ever state visit to Beijing in order to sign the agreement.

However, New Zealand says it was not properly consulted over the plans, leading to what Prime Minister Christopher Luxon has described as a “dispute”.

The Cook Islands is hugely reliant on New Zealand under a longstanding “free association” agreement that provides it with defence and financial support. China’s growing influence in the Pacific has challenged the US and its allies, who have held sway for years.

“We value our partnership with New Zealand and we expect the same respect,” Brown said at a press conference last week. He was due to travel to China on Monday.

“Disagreements, although difficult, are an inevitable part of international relations but they should never define the entirety of our engagement.”

He has denied any dispute, saying “engagement has been consistent, respectful and open” and that the Cook Islands has the right to forge its own path as a self-governing country.

China’s foreign ministry said that both countries were important partners and that it was ready to work with the Cook Islands to “achieve new progress”.

“The China-Cook Islands relationship is not targeted at any third party and should not be subject to or be disrupted by any third party,” said spokesman Guo Jiakun.

Beijing has had diplomatic ties with the Cook Islands since 1997 and is one of its development partners.

Under their 60-year-old agreement, the Cook Islands is self governing in “free association” with New Zealand. The two countries are expected to consult each other over issues of defence and security. Brown says the new agreement with China will cover areas including infrastructure, trade and tourism.

Deep deep-sea mining is also expected to be part of the deal. Brown believes that mining valuable minerals on the seabed could be a game-changer for the Cook Islands, creating huge economic wealth.

However, the practice, in which China is a major player, is controversial, and critics believe it will exacerbate climate change – to which the Cook Islands are already vulnerable.

Luxon said on Monday that while New Zealand had “very good relations between the Cook Islands and its people”, in this case there had not been transparency.

Asked at a press conference whether he would consider putting aid to the Cook Islands on hold, as it recently did for Kiribati due to a diplomatic snub, Luxon said he would wait to see what was in the deal.

Under the free association agreement Cook Islanders can live, work and access healthcare as New Zealand citizens – benefits some fear they could lose if relations between the two countries further sour.

There has also been criticism from some that Brown and his government did not consult the public about the China deal first – something Tina Browne, the leader of the Democratic Party, has described as “insane”.

Both she and fellow opposition leader Teariki Heather, from the Cook Islands United Party, say they have lost confidence in Brown’s leadership.

That is despite his recent U-turn on a controversial proposal to introduce a separate passport for Cook Island citizens, while also allowing them to retain New Zealand citizenship. Wellington rejected the plan last year.

The Cook Islands is not the first Pacific Island nation to strengthen its ties with China. The Solomon Islands signed a security pact with Beijing in 2022, while countries including Vanuatu and Papua New Guinea also have close relations.