China has heavily criticised New Zealand's support of Taiwan joining the World Health Organisation, saying the "erroneous remarks" could damage relations between the countries.
Foreign Ministry spokesperson Zhao Lihan told a press conference on Monday China "deplores and opposes" New Zealand's position, and "no one should entertain any illusion when it comes to matters concerning China's core interests".
"We hope that certain people in New Zealand will stop spreading rumours and creating trouble and work to enhance instead of undermining bilateral mutual trust and cooperation," Lihan said.
New Zealand Foreign Minister Winston Peters on Thursday said Taiwan had been a "standout world success story on Covid-19", and that New Zealand had joined others in asking for the island nation to be added to World Health Organisation (WHO) as an observer.
The building support for Taiwan entering the WHO has angered China, which ardently believes Taiwan lacks sovereignty and is part of China's territory.
Beijing refuses diplomatic relations with countries that consider Taiwan a sovereign nation, part of a strategy called the "one-China policy".
Lihan on Monday said the one-China policy "must be observed", and claimed Taiwan was using the outbreak to seek independence.
"The one-China principle is the political foundation of China-New Zealand relations ... China urges New Zealand to strictly abide by the one-China principle and immediately stop its wrong actions on Taiwan-related issues to avoid damaging bilateral relations."
Lihan appeared to contradict a claim from Peters that discussions with Chinese Foreign Minister Wang Yi had given him confidence there would be no pushback.
"I wonder how he came to that assumption? I want to point out that China is committed to developing friendly cooperative relations with New Zealand based on mutual respect and equality. But we are firmly resolved to uphold our sovereignty, independence and territorial integrity."
On Tuesday, Prime Minister Jacinda Ardern told TVNZ New Zealand's support of Taiwan entering the WHO as an observer, "does not change New Zealand's position on a one-China policy".
Finance Minister Grant Robertson said the diplomatic war of words would not damage bilateral relations.
"There is a place for Taiwan as an observer, they have a lot to offer from their experience of Covid-19," he said.