The Prime Minister's office is demanding a Chinese immigration agency remove a picture of John Key from its website, which appears to show he endorses the organisation.
The China-based agency's website said it had been working in New Zealand immigration for 10 years and claimed to have helped with 20,000 applications.
It prominently featured a large picture of Mr Key, his signature, and the words "recommended to you with sincerity by John Key".
Several other images of Mr Key with Chinese officials were on the site. The agency said it had a "fast government channel to reach New Zealand directly" and a strategic partnership with the New Zealand Government. "We promise you can to get your visa 100 per cent for certain," the website says. "We are the only authorised immigration agency in China that works only on New Zealand applications."
But New Zealand officials said the claims on the website were false.
A spokeswoman for Mr Key said he was not aware of the use of his picture.
"It is a completely unacceptable use of the Prime Minister's image and we will be writing to the website hosts insisting they remove this content."
The website's administrators, based in Shenzhen, did not respond to questions about the use of Mr Key's picture. Officials did not know how long it had been on the site. It is understood that it's not the first time Chinese websites have falsely claimed connections to Mr Key.
The agency claimed visa applications for New Zealand took just 60 days and that 100 per cent of them were successful.
Its website also included pictures of former Prime Minister Helen Clark, New Zealand diplomats and broadcaster John Campbell.
Mr Key is on a trade-focused trip to China this week and has a high profile in the country.
He has featured on the front page of the People's Daily and in articles by the state Xinhua News Agency, Beijing News and Shanghai Times.
Endorsement by high-ranking officials and individuals is extremely important to Chinese business.