Tonga's deputy prime minister Samiu Vaipulu says he will not allow a third-party assessment on the controversial MA60 aircraft gifted by China.
Matangi Tonga online says the government's refusal to bring an international aviation authority to certify the plane has strained Tonga's relationship with New Zealand.
New Zealand's Foreign Minister Murray McCully reiterated last month he would continue to withhold a tourism development aid package for Tonga worth about eight million US dollars until the aircraft was certified by a respected international authority.
New Zealand even offered to fund an aviation safety expert to go to Tonga and assess the aircraft.
But Mr Vaipulu told Matangi Tonga that he could not allow a third-party assessment because it would be bad for Tonga's diplomatic relation with China.
He says China has generously given Tonga a 15-million US dollar aircraft along with 13 million US dollars worth of spare parts to keep the aircraft running for three years.
He said bringing in a third party to check on what China has given them would be like stabbing the Chinese in the back, something Tonga can't do.
Mr Samiu also adds China has offered to give Tonga two new Y12 aircraft, to enable Tonga's domestic air service to extend to the Niuas, and 'Eua.
The two aircraft were scheduled to arrive in 2015, but they were negotiating with the hope of having the first Y12 aircraft arrive in Tonga in next May.