A group of senior Conservatives has written to Tory MPs expressing concerns over the Government's controversial move to allow Chinese tech giant Huawei a role in the UK's 5G network, according to reports.

The letter is from four former cabinet members, including ex-Tory leader Sir Iain Duncan Smith, the BBC said.

It comes as US vice-president Mike Pence indicated the decision by Prime Minister Boris Johnson to allow Huawei a limited role in 5G roll-out could jeopardise a post-Brexit trade deal between Britain and America.

The letter from, among others, Owen Paterson, David Davis and Damian Green states some MPs were "working to find a better solution" to the 5G issue, according to the BBC.

READ MORE: Poll shows 43% of Brits disagree with Huawei 5G network rollout

The senior Tories want "high-risk" vendors to be ruled out immediately, or phased out over time.

The letter states: "We are seeking to identify a means by which we ensure that only trusted vendors are allowed as primary contractors into our critical national infrastructure.

"Trusted vendors would be companies from countries that have fair market competition, rule of law, respect human rights, data privacy and non-coercive government agencies."

Pressed on whether the Huawei decision could be a deal-breaker in Brexit trade talks, Pence told CNBC: "We'll see. We'll see if it is."

Referring to the UK move to allow Huawei limited participation in the 5G rollout, Pence said: "We are profoundly disappointed because, look, when I went at the president's direction in September I met with Prime Minister Johnson and I told him the moment the UK is out of Brexit we were willing to begin to negotiate a free trade arrangement with the UK.

"But we just don't believe that utilising the assets, the technology of Huawei is consistent with the security or privacy interests of the UK, of the United States, and it remains a real issue between our two countries."

The remarks came after it was reported that US President Donald Trump blasted the Prime Minister with "apoplectic" rage during a heated phone call regarding the 5G move.