Open this photo in gallery Visitors look at a display for 5G wireless technology from Huawei at the PT Expo on Sept. 26, 2018, in Beijing. Two U.S. Senate intelligence committee members want Canada to follow their country and Australia's lead in blocking the Chinese technology firm from supplying equipment that will connect future smartphones to the internet and telephone network. Mark Schiefelbein/The Associated Press

Two influential members of the U.S. Senate select intelligence committee have written Prime Minister Justin Trudeau, urging him to bar Chinese telecom equipment giant Huawei from Canada’s next-generation 5G mobile network on the grounds the Shenzhen-based firm represents a significant security risk.

These American concerns cross party lines. The pair are Republican Senator Marco Rubio and Democrat Senator Mark Warner, vice-chair of the intelligence committee. They want Canada to follow the lead of the United States and Australia in blocking Huawei from supplying equipment that will connect future smartphones to the internet and telephone network.

The senators caution Mr. Trudeau that allowing Huawei into Canada’s next era of wireless infrastructure could interfere with intelligence sharing between key allies and impair cross-border co-operation in telecommunications between U.S. and Canadian firms.

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“We write with grave concerns about the possibility that Canada might include Huawei Technologies or any other Chinese state-directed telecommunications company in its fifth-generation (5G) telecommunications network infrastructure,” Mr. Rubio and Mr. Warner wrote Mr. Trudeau in an Oct. 11 letter obtained by The Globe and Mail.

“As you are aware, Huawei is not a normal private-sector company. There is ample evidence to suggest that no major Chinese company is independent of the Chinese government and Communist Party − and Huawei, which China’s government and military tout as a ‘national champion,’ is no exception.”

The senators raise the prospect that a Canadian embrace of Huawei technology in its 5G networks could affect the sharing of sensitive and confidential information between Five Eyes intelligence-sharing allies. The United States, Britain, Canada, Australia and New Zealand constitute the Five Eyes, which allows police, prosecutors and spies to exchange information to prevent espionage and terrorism.

“We are concerned about the impact that any decision to include Huawei in Canada’s 5G networks will have on both Canadian national security and ‘Five Eyes’ joint intelligence co-operation,” Mr. Rubio and Mr. Warner wrote.

The senators further warn that the presence of Huawei in Canada’s 5G network could damage co-operation between the United States and Canada on telecommunications matters. “The strong alignment between the United States and Canada in spectrum management has meant that American and Canadian carriers in many cases share complementary spectrum holdings, jointly benefiting from economies of scale for equipment designed for regionally harmonized frequencies. The entry of suppliers such as Huawei into the Canadian market could seriously jeopardize this dynamic, depriving both Canadian and American operators of the scale needed to rapidly build out 5G networks.”

The senators say they were troubled last month, when Canada’s top cybersecurity official, Scott Jones, rejected the idea of banning Huawei on the grounds that this country’s safeguards are adequate to mitigate any risk. The new head of Ottawa’s Canadian Centre for Cyber Security − which is part of Canada’s Communications Security Establishment spy agency − told MPs in September that Canada has a “very advanced relationship with our telecommunications providers, something that is different from most other countries.”

Mr. Rubio and Mr. Warner warned that Canada’s safeguards are not enough. “While Canada has strong telecommunications security safeguards in place, we have serious concerns that such safeguards are inadequate given what the United States and other allies know about Huawei.”

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Under Chinese law, companies must “support, co-operate with and collaborate in national intelligence work” as requested by Beijing, and security experts in the United States and Canada warn that equipment produced by firms such as Huawei could be compromised on behalf of China’s ruling party.

The chiefs of six U.S. intelligence agencies and three former heads of Canada’s spy services have said publicly they consider Huawei one of the world’s top cyberintelligence threats and that its 5G technology could be used to conduct remote spying, maliciously modify or steal information, or even shut down systems.

Mr. Rubio and Mr. Warner noted the warnings earlier this year from Canadian national-security officials against the inclusion of Huawei in Canada’s 5G networks and singled out comments from former Canadian Security Intelligence Services director Ward Elcock, who told The Globe and Mail in March that Huawei should be excluded. "I have a pretty good idea of how signal-intelligence agencies work and the rules under which they work and their various operations,” Mr. Elcock said at the time. “I would not want to see Huawei equipment being incorporated into a 5G network in Canada.”

Mr. Trudeau has previously declined to say whether Canada might ban Huawei. “We will make decisions based on the facts, on evidence and what is in the best interests of Canadians,” Mr. Trudeau said in August when asked about this.

The next generation of wireless technology, 5G, will require a vast increase in the number of small cell sites – smaller versions of cell towers – to provide a dense web of coverage to deliver faster downloads and almost no lag time.

Huawei, the world’s largest maker of telecommunications equipment and the No. 3 smartphone supplier, has been shut out of the giant U.S. market as well as Australia because of national-security concerns. Japan is also studying whether to impose regulations to reduce the security risks from using network equipment from Chinese manufacturers including Huawei.

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In the case of Australia, the U.S. senators noted, Canberra effectively banned Huawei, fellow Chinese telecom equipment maker ZTE and other Chinese state-directed companies from its 5G networks by excluding firms that “are likely to be subject to extrajudicial directions from a foreign government" and, therefore, “pose unacceptable risks to national security.”

Moreover, they noted, Britain’s Huawei Cyber Security Evaluation Centre Oversight Board’s 2018 annual report to Britain’s national-security adviser found that “identification of shortcomings in Huawei’s engineering processes have exposed new risks in the U.K. telecommunications networks and long-term challenges to mitigation and management" there.

“Given the strong statements by former Canadian national security officials as well as similar concerns out of the U.S., Australia, and the United Kingdom, we hope that you will reconsider Huawei’s inclusion in any aspect of Canada’s 5G development, introduction, and maintenance,” Mr. Rubio and Mr. Warner wrote.

They urged Mr. Trudeau to talk to U.S. intelligence officials.

“Should you have any questions about the threat that Chinese state-directed telecommunications firms pose to your networks, we urge your government to seek additional information from the U.S. intelligence community.”

Huawei Canada has always said the firm has worked openly and transparently with the Canadian government and domestic telecoms for a decade to satisfy national-security concerns.

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The Prime Minister’s Office declined to comment on the matter.