Winston Peters did not hold back in his description of Simon Bridges' interview with Chinese state media, mocking it as "subservient grovelling".
Peters, the Deputy Prime Minister, used his speech in Parliament on Wednesday to criticise the interview Bridges gave Chinese state media during his visit to the superpower earlier this month.
"I have never heard such obsequious, subservient grovelling, kowtowing, palm-kissing nonsense," Peters, also New Zealand First leader, said.
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He is the latest MP to attack the interview, after Finance Minister Grant Robertson described it last week as the "most extraordinary interview I think I've ever seen the leader of a National Party give".
The National leader's interview with state-owned news channel CGTN made world news, with The Guardian highlighting how it had been described as "alarming".
Bridges praised the Communist Party of China (CCP) for taking the country from mass poverty to economic prosperity in the state media interview, calling it an "amazing story".
Peters said the interview was "staggering" because he "belongs to a country that for all these decades and down through the years... has been a democracy".
The People's Republic of China - with a population of around 1.4 billion - is a unitary one-party state.
The country's President Xi Jinping is effectively allowed to remain in power for life after China's Congress passed a constitutional change last year to remove the two-term limit on the presidency.
Peters said New Zealand stands for "the rule of law, believes in protection - not persecution by government... reason, fairness and equality, and dare I say it is as a model of transparency".
He said former New Zealand PMs Sidney Holland (1949-1957), Keith Holyoake (1957), John Marshall (1972) and Robert Muldoon (1975-1984) would be "turning in their graves" if they heard the interview.
"What an amateur let loose on an international stage... Unbelievable."
Simon Bridges has been contacted for comment.
Bridges told Magic Talk on Monday that he is "no apologist for China" in his defence of the interview.
He also doubled down on his defence of meeting with Guo Shengkun who is responsible for China's Ministry of State Security (MSS), described as a combination of the CIA and FBI.
Canterbury University Professor Anne-Marie Brady, an expert on Chinese politics, tweeted about the meeting, describing Shengkun as "in charge of China's secret police".
Bridges pushed back on that description last week, saying it was an "unfair characterisation" of the man he met.
Bridges said he discussed areas of concern where he could, such as the tense relations between China and Hong Kong, and secretive camps in China's Xinjiang province reportedly holding Uyghurs and other Muslim minorities captive.
He said in the interview: "We understand and accept China's sovereignty in Hong Kong," adding that it should be resolved "peacefully."
Brady noted how Bridges' delegation to China included Yang Jian, a National MP, who in 2017 admitted training Chinese spies so they could monitor other countries' communications.
China is New Zealand's largest export destination following the signing of a 2008 bilateral Free Trade Agreement.
It accounts for nearly $NZ15.3 billion and 24 percent of total exports.