New Zealand will not shy away from criticising China's human rights record to protect its lucrative trade relationship with Beijing, Prime Minister Jacinda Ardern has said in an interview.

Ardern's government is accused of going easy on China's much-questioned humanitarian record, prompting some commentators to label Wellington a "weak link" in the US-led Five Eyes security alliance.

But the New Zealand leader rejected suggestions that economic ties with her country's largest trading partner were muting her ability to voice broader concerns.

"It is very important to us that we maintain integrity in the way that we conduct our diplomatic relationships," she said in a joint interview with AFP, the New Zealand Herald, NBC News and Covering Climate Now.

Ardern noted "heightened tensions" between China and Australia, which has been hit with punitive sanctions by Beijing over its outspoken stance on issues such as the treatment of Uyghurs and the erosion of democracy in Hong Kong.

New Zealand has also raised concerns about the same issues, but has been more restrained in its statements and has not faced any economic retaliation.

Ardern's government declined to support a parliamentary motion in May labelling the treatment of Uyghurs as genocide, saying the legal case to use the term had not been made and instead expressed "grave concern".

New Zealand has also said it is "uncomfortable" using the Five Eyes group -- comprising the United States, Canada, United Kingdom, Australia and New Zealand -- to criticise China on rights issues.

But Ardern insisted New Zealand's diplomatic ties with China were not determined by trade.

"We have the maturity in our relationship to raise issues that we're concerned about, be it human rights issues, be it labour issues, be it environmental issues," she said. 

"And it's very important to us that we continue to be able to do that and do that regardless of those trading ties."

Asked if she would classify China as an ally or an adversary, she replied: "I don't think we would determine our relationship with any country in such stark terms."

Ardern said earlier this year that New Zealand's differences with China on human rights were becoming "harder to reconcile", but her government would continue to point out areas of concern to Beijing.