Canada should ban China's Huawei Technologies from supplying equipment to Canadian 5G networks because the security risk is too great, a former spy chief said in an article published on Monday.
China's ambassador last week threatened repercussions if Ottawa blocked Huawei, a warning the Canadian government dismissed.
Relations between the two nations have soured since a top Huawei executive was arrested in Vancouver last month on a U.S. extradition warrant.
Canadian officials are studying the security implications of 5G networks, the latest generation of cellular mobile communications, but their report is not expected in the immediate future, a source close to the matter said last week.
Richard Fadden, who served as the head of the Canadian Security Intelligence Service spy agency from 2009 to 2013, cited what he said was mounting evidence for blocking Huawei.
"Canada's government should ignore the threats and ban Huawei from Canada's 5G networks to protect the security of Canadians," he wrote in the Globe and Mail.
Some Canadian allies have already imposed restrictions on using Huawei equipment, citing the risk of espionage.
Public Safety Minister Ralph Goodale on Monday told reporters that other companies could supply equipment for future 5G networks but did not give details.
China detained two Canadians last month after the arrest of Meng Wanzhou, Huawei's chief financial officer and the founder's daughter, and demanded she be released. A court later retried a Canadian who had already been jailed for drug smuggling and sentenced him to death.
"If China would resort to putting Canadians to death to defend its corporate national champion, what might it do if the Chinese Communist Party had unfettered access to Canada's vital communications networks?" said Fadden.
Neither Huawei nor the Chinese embassy responded to requests for comment.
A group of 143 academics and former ambassadors from around the world on Monday released an open letter to Chinese President Xi Jinping, urging him to free the two detained Canadians.
"(We) must now be more cautious about traveling and working in China and engaging our Chinese counterparts," they wrote.
"That will lead to less dialogue and greater distrust, and undermine efforts to manage disagreements and identify common ground. Both China and the rest of the world will be worse off as a result."
John McCallum, Canada's ambassador to China, said last Friday that his top priority was the release of the two detainees and scrapping the death penalty for the condemned man.
(Reporting by David Ljunggren; Editing by Marguerita Choy and Sandra Maler)