It is alleged that Chinese-born Jian Yang, 55, was investigated by New Zealand's intelligence services for his links to Chinese military academies.
But National's Jian Yang says to him they were just students collecting information by monitoring the communications of other countries.
Yang said he'd taught university students English language and American studies.
Prime Minister Bill English and the National Party needed to "seriously explain themselves", over the issue, Peters said.
'This is a smear campaign by nameless people who are out to damage me and the National Party ten days from an election, just because I am Chinese, ' Dr Yang said.
"Members of the Chinese community in New Zealand would have been obliged to respond to any fundraising request from him as a few would have been aware of his background, and present links to their homeland. If you define it that way, then they are spies".
FT said he "has consistently pushed for closer ties" with China, and also "for global policies that echoed those of the Chinese Communist Party".
This is likely what has SIS anxious - particularly as New Zealand shares national security information with the four other major anglophone countries (the U.S., the U.K., Australia, and Canada), and as Yang had sat on the parliament's select committee for foreign affairs, defense, and trade from 2014 to 2016.
A spokesman for China's ministry of foreign affairs said it did not usually comment on the internal affairs of other countries - but stated "we are firmly opposed to false reports, groundless accusations and falsifications from some media".
'I have been nothing but upfront and transparent about my education and employment, ' he said.
"I refute any allegations that question my loyalty to New Zealand ..." This is not a spy thriller from the airport bookshelves, " said Mr Peters, campaigning in the southern city of Dunedin today.
One is the Air Force Engineering Academy of China's People's Liberation Army (PLA), where he studied English language as an undergraduate and subsequently taught. The Financial Times said the latter institution specializes in training military intelligence officers and deep cover agents.
"You get to know people as MPs and I think from early on I've been aware that he had military training including military intelligence", he said. "But once they understand the system, they should be assured that this is nothing, really, you should be concerned about".
Peters said Chinese interests were "starting to dominate the lives of New Zealanders and clearly our economic direction". "Although I was not born here I am proud to call myself a New Zealander, obey our laws and contribute to this country", he told a press conference.