Senior Tory MPs have expressed alarm about Theresa May’s readiness to give the Chinese telecoms firm Huawei a limited role in supplying the future 5G mobile phone network against the advice of some cabinet ministers, security chiefs and the US.

Huawei will be banned from supplying core parts of the network but will get a role in non-core technology, according to leaks from a meeting of the national security council (NSC).

Any potential role for the company in the future network has alarmed senior Conservatives, including the chairman of the defence select committee, Julian Lewis, and his counterpart on the foreign affairs select committee, Tom Tugendhat.

Lewis raised the issue at prime minister’s questions on Wednesday when he pointedly asked whether the government accepted Huawei was “intimately linked with the Chinese Communist government and its deeply hostile intelligence services”.

Standing in for the prime minister, her de facto deputy, David Lidington, said: “Legally speaking Huawei is a private firm, not a government-owned company.”

Earlier, Tugendhat said as part of his role he had been briefed by security officials that it was difficult to make a distinction between core and non-core activities involving 5G because of the speed and capability of the system. “This is a concern that has been raised extremely clearly to me,” he told BBC Radio 4’s Today programme.

Q&A What is Huawei and why is its role in 5G so controversial? Show Hide Fast-growing Huawei is arguably China’s first global multinational. The Shenzhen-based company makes mobile phones, base stations and the intelligent routers that facilitate communications around the world. But its success increasingly concerns the US, which argues Huawei is ultimately beholden to the Chinese Communist party and has the capability to engage in covert surveillance where its equipment is used. Huawei is by some distance the world’s largest supplier of telecoms equipment with an estimated 28% market share in 2019. It was also the second largest phone maker in 2019, after Samsung and ahead of Apple. But Australia banned Huawei from 5G in 2018, with its spy agencies declaring they were worried the company could shut down power networks and other parts of its infrastructure in a diplomatic crisis. Trump banned US companies from working with Huawei last year and has strenuously lobbied others to follow suit, venting “apoplectic fury” in a phone call to Boris Johnson after the UK agreed to allow the Chinese company into 5G. The company had successfully targeted the UK early on. It has supplied BT since 2003 and gradually expanded to the point where it agreed to create a special unit in Banbury, known as the Cell, where the spy agency GCHQ could review and monitor its software code. Vodafone is another key customer. Britain’s intelligence agencies said in January that any Huawei risk could be managed as long as the company was not allowed to have a monopoly. As a result, Boris Johnson concluded Huawei’s market share should be capped at 35% for forthcoming high-speed 5G networks. In July 2020 the UK position changed, and it was announced that Huawei is to be stripped out of Britain’s 5G phone networks by 2027. Oliver Dowden, the UK culture secretary, also announced that no new Huawei 5G kit can be bought after 31 December 2020 – but said that older 2G, 3G and 4G kit can remain until it is no longer needed. Dan Sabbagh Defence and security editor Photograph: Mark Schiefelbein/AP

Asked if supplying an antennae presented a low risk, Tugendhat said: “No, an antennae obviously carries the communication system and this is exactly the point that was made very clearly to me by one of our Five Eyes intelligence partners.”

He added: “The reality is we are talking about a system here that will need constant upgrading, and every time you do that you’ve got to open up the system to your technology partner to make sure it works.

“The Chinese government is experimenting in extremely – how can I put it politely – adventurous ways of expanding an intelligence state into a domestic infrastructure.

“They are bound by Chinese law and Chinese law does oblige them to cooperate with the security apparatus of the Chinese state. This does mean it is unwise to cooperate on an area of critical national infrastructure like telecoms with a state that can best be described as not always friendly.”

Margot James, the digital minister, appeared to confirm the leaks, tweeting that the advice of GCHQ’s National Cyber Security Centre, responsible for monitoring Huawei, was that “we can manage/minimise any risk Huawei might pose to telecoms infrastructure and Theresa May is absolutely right to act on that advice”.

She added, however, that no final decision had been made on the Chinese firm and 5G supply, despite the leaks from Tuesday’s cabinet-level meeting. Whitehall sources indicated their view on Huawei was as James had stated, adding that countries such as Germany also thought the risk was manageable.

Jeremy Fleming, the director of GCHQ, said a final decision on Huawei would be formally announced by the culture secretary, Jeremy Wright, in due course.

Speaking to a cybersecurity conference in Glasgow, the spy chief said GCHQ was offering expert advice, but added that concerns about Huawei’s home country were not the top priority.

“We are looking at the risks that arise from their security and engineering processes, as well as the way these technologies are deployed in our national telecom networks,” Fleming said. “The flag of origin of 5G equipment is important but it is a secondary factor.”

Tory concerns were underlined by Mark Pritchard, a former member of the joint committee on national security strategy, George Freeman, a former minister and No 10 adviser, and a former army reserve Bob Seely.

Mark Pritchard MP (@MPritchardUK) Allowing Huawei to build the UK's 5G network could expose the UK's critical national infrastructure to additional 'risk' and is causing serious concerns amongst many in the #FiveEyes intelligence community & Parliamentarians with oversight on cyber issues. Time for a rethink....?

George Freeman MP (@GeorgeFreemanMP) I fear this may prove to be a bad decision, with major strategic #datasecurity & contract issues. Only a few weeks ago the excellent @TurnbullMalcolm⁩, former Prime Minister of Australia, was here warning against this very decision. https://t.co/MmcphBb8Dd

Bob Seely MP (@IoWBobSeely) A bad and short-sighted decision which fails to heed the warnings of US and Australian experiece. I fear that this has not been thought through or treated with the importance it deserves. https://t.co/iOCQI7i0hM via @Telegraph

Some of the UK’s allies, notably the US, have taken a tougher stance against Huawei. Chinese companies are banned from working on critical telecoms infrastructure in the US. Mike Pence, the vice-president, called on “all our security partners to be vigilant”.

The former US homeland security adviser Tom Bossert said May appeared to be ignoring the advice of her security chiefs.

He told Today: “What we see seems to, from the outside, undercut some of her senior security officials and their recent comments in general about cybersecurity and specifically about Huawei’s poor performance over the last year … I’m not sure what the prime minister was thinking but it seems to be against the advice of some of her security professionals.

“I think it is a little overly rosy and optimistic to suspect that [risks] can be mitigated in new 5G infrastructure … Some are concerned that Huawei represents a future espionage risk, that there will be theft of information and some believe a future sabotage risk.”