The Tongan Deputy Prime Minister has told New Zealand to stop interfering with its internal policies, as a travel advisory continues to warn tourists away from Tonga.
Samiu Vaipulu says the controversial MA-60 aircraft gifted by China is fully accredited.
The International Civil Aviation Organisation says Tonga can accredit the plane, but New Zealand is within its rights to ask questions of it.
But Mr Vaipulu says that would be fine if the flights were to New Zealand, but the plane is on a domestic route.
Mr Vaipulu says China is happy for New Zealand's Foreign Minister Murray McCully to send an expert to China to inspect the plane, but Tonga has no issue with it.
"I think he's treating us unfairly. He should have the travel advisory as well to the other 20 countries that are using the MA-60 and has China has also agreed to have someone from New Zealand, whatever his concerns are, he can check it in China."
Tonga's Deputy Prime Minister, Samiu Vaipulu.