Boris Johnson faces plunging into diplomatic deep freeze with Donald Trump over fears a Chinese tech giant will be allowed into Britain's 5G system within days.
Reports today suggest Huawei will get the green light to help build the fast phone network, despite national security concerns.
An announcement is expected on Wednesday.
The issue was raised in a phone call on Friday night between the Prime Minister and Donald Trump - who is vehemently against Huawei taking a role in the UK.
The President reportedly said the UK and US should build an alternative network - while US Treasury Secretary Steven Mnuchin warned it is "critical" to protect infrastructure from China.
But UK officials want to go ahead with the Chinese firm, it is claimed.
The row could overshadow Boris Johnson's bid to celebrate Brexit on Friday night with an imminent US trade deal - and it could also ignite a UK Cabinet split.
Reports say Home Secretary Priti Patel is furiously opposing the attempt to approve Huawei’s bid for the UK’s 5G network.
Sources told the Sunday Times she was "on the warpath" along with Defence Secretary Ben Wallace to fight back against any Huawei involvement.
She told Sky News today: “That’s not accurate and you shouldn’t take too literally what you’re reading in the Sunday newspapers.”
But Ms Patel - who is still in talks at the secretive National Security Council - repeatedly emphasised she would protect the “national security” of the UK.
And she refused to deny any specific details of today’s reports, saying: “We will have those discussions, we’ll have them privately and I’m not going to comment on speculation.”
No10 and the White House said the two leaders discussed "working together to ensure the security of our telecommunications networks" in their call on Friday.
Treasury Secretary Steven Mnuchin was expected to raise the issue in talks with Sajid Javid on Saturday morning.
He said: "As more and more things are connected to the network and to the grid, these national security issues go beyond the traditional aspects.
"I think the real issue for us is making sure that the networks and infrastructure are properly protected."
Last year, the US imposed trade restrictions on Huawei over concerns about the company's security and ties to the Chinese government.
Allegations that their telecommunications equipment could be used, for example by the Chinese state, to spy on people has been repeatedly denied by the tech giant.
A final decision by the National Security Council of senior ministers is widely expected in the coming week.
