MP Olivia Chow has lashed out at the country’s spy agency for claiming foreign agents are influencing Canadian politicians, and has urged Prime Minister Stephen Harper to denounce the “baseless” charges of CSIS chief Richard Fadden before they damage international relations.

“As the leaders of the G20 start arriving in Canada, let us not give in to the politics of fear being peddled by former or current CSIS officials,” the Hong Kong-born Ms. Chow told a hastily arranged news conference Thursday in Toronto, host of this weekend’s summit.

“Baseless spy stories belong in novels and movie theatres,” she said, adding Mr. Fadden’s comments, aired Tuesday by the CBC, “need to be condemned by the Prime Minister of Canada.”

Mr. Fadden, head of the Canadian Security Intelligence Service, caused a furor when he suggested foreign agents, possibly Chinese, have been pulling strings in Canadian politics. He named no one, but said two provincial cabinet ministers were among officials under influence.

Facing an uproar, Mr. Fadden backtracked and said CSIS was not concerned enough to report the cases to provincial authorities or the federal government’s nerve centre, the Privy Council Office.

Ms. Chow, a New Democrat MP from downtown Toronto and wife of NDP Leader Jack Layton, said Canadians deserve a far fuller explanation.

“Make public the files on all elected officials, name names and give evidence,” she said. “Hiding in the shadows and making blanket statements is harmful and destructive.”

Asked if she thought CSIS had a file on her, Ms. Chow said, “I have no idea. If there is, let’s see the file.”

The Prime Minister’s Office declined to comment on Mr. Fadden’s claims or Ms. Chow’s statements. “The director of CSIS has clarified his comments,” spokesman Andrew MacDougall said.

Meanwhile, the PMO released a statement Thursday trumpeting bilateral discussions between Mr. Harper and Chinese President Hu Jintao in Ottawa, where agreements on tourism, the environment, crime and beef exports to China were signed.

For years, CSIS has raised concerns about China planting foreign operatives in Canada to clandestinely steal secrets, quell dissent in diaspora communities or influence politics.

A 2009 book co-authored by an ex-CSIS agent claimed a “Chinese lobbying organization” in Canada, backed by spies, had convinced MPs to pass a motion in 2007 urging Japan to apologize for atrocities during the Second World War. The motion, unanimously approved in the Commons, was brought forward by Ms. Chow, though she wasn’t named in the book.

The organization, ALPHA (Association for Learning and Preserving the History of WWII in Asia), was also not named, but it sued for libel and won a settlement. The book was reissued with the relevant passages removed.

Ms. Chow was flanked at the news conference by ALPHA founder Joseph Wong, at the agency’s Toronto offices. Mr. Wong, a Hong Kong-born physician who has lived in Canada since 1968, said he was “particularly incensed” when Mr. Fadden backed away from his initial comments.

“There’s a natural question: If there is no solid evidence, why the accusation in the very beginning? On what basis did he make the accusation? Is it on the basis of our skin colour?”

Mr. Wong said ALPHA, which promotes instruction in Canadian schools about the Second World War’s impacts in Asia, has scrupulously avoided dealings with the Chinese government other than to arrange educational trips to China for Canadian teachers. He called on other MPs and the Prime Minister to speak out on the CSIS chief’s remarks.

“There’s no question that we will not allow anyone to cast a doubt on our loyalties in this country,” Mr. Wong said.

Few have felt the brunt of the spy service’s fears like Haiyan Zhang, a Chinese-born Canadian and rising star in Ottawa’s civil service until she reached its core, the Privy Council Office, in 2003.

Ms. Zhang was fired after a CSIS security-screening investigation cited her previous work in Cairo as a journalist for Xinhua, the Beijing-controlled news service, and her attendance at receptions in Ottawa co-hosted by the Foreign Affairs department and the Chinese embassy.

“What is most disturbing about this CSIS allegation [by Mr. Fadden] is that such sweeping statements are accepted as facts without any evidence being presented,” Ms. Zhang said. “If there are proven spies, they should be ousted and charged as they do in the United States. If not, then stop such propaganda which only helps to alienate us and create distrust among all Canadian citizens.”