U.S. Secretary of State Mike Pompeo has warned the UK that it risks undermining its sovereignty if it allows Huawei to become part of its 5G network.

British Prime Minister Boris Johnson is expected as early as this week to announce that the Chinese company will be allowed some part in rolling out the technology following pleas from business that a ban would be highly damaging.

However, following longstanding threats that security co-operation will be threatened in that scenario, the US is stepping up its warnings.

"The UK has a momentous decision ahead on 5G," Pompeo tweeted, continuing: "British MP Tom Tugendhat gets it right: 'The truth is that only nations able to protect their data will be sovereign.'"

Tugendhat, a member of Johnson's ruling Conservative Party is an opponent of Huawei's involvement but nevertheless accepts that it will be difficult to completely exclude the company because its equipment is already in use in the existing 4G infrastructure.