John Sawers, who served as the chief of MI6 from 2009 to 2014, played down national security concerns over the Chinese tech giant, telling an audience in London that Beijing has not "sought to exploit, or been able to exploit, Huawei equipment in our telecoms national infrastructure" for espionage.
Intelligence officials in the U.S. have expressed concerns that the company could set up "backdoors" to help the Chinese government spy on Americans. For its part, Huawei has denied it would ever hand over data to Beijing.
MI6's current chief, Alex Younger, last year flagged concerns about companies like Huawei, specifically targeting "Chinese ownership of these technologies" as a primary risk. Under Chinese law, companies are obliged to hand over data to assist state intelligence.
The Chinese firm has faced intense scrutiny in the U.S., which has added it to a trade blacklist and is looking to extradite its CFO, Meng Wanzhou, from Canada on bank and wire fraud charges. The company's CEO — and Meng's father — Ren Zhengfei recently said he is considering offering an exclusive 5G license to a U.S. carrier.
Washington upped the pressure on China's tech industry earlier this week. It placed another 28 entities on the trade blacklist, alleging they have been implicated in human rights violations related to minority Muslims in northwest China.
Sawers said that Huawei had become a "point of leverage" in the trade battle between the U.S. and China, and that President Donald Trump's administration would likely make concessions on its tough stance on the firm.
He did however warn that "we would be very vulnerable to be exploited" if the West were to rely solely on network kit from Huawei and fellow Chinese telecommunications firm ZTE.
"There would be wider concerns if Chinese providers were the dominant suppliers into the U.K. system," Sawers said in response to a question from CNBC. He added that British defense mechanisms "would not be as robust" if that were the case.
In Britain, the government has not yet revealed whether it will allow Huawei access to its 5G networks. A report earlier this year said the country would let Huawei provide "non-core" gear, like antennas, to mobile network operators. U.K. Digital Secretary Nicky Morgan said the country would take a decision on the matter "by the autumn."
Sawers told CNBC that there would be ways to "mitigate and manage security risks" even if suppliers like Huawei were allowed to play a role in parts of the U.K.'s 5G infrastructure.