A delegation of US officials was sent to the UK on Monday to convince the UK to ban Huawei equipment from its 5G infrastructure.

The US has been warning allies for over a year that it may have to restrict intelligence-sharing with countries that don't ban Huawei, as it views the Chinese tech company as a national security threat.

According to The Guardian, the delegation told British lawmakers it would be "nothing short of madness" to keep using Huawei kit, and added "Donald Trump is watching closely."

Analysts at Assembly Research estimated that freezing out Huawei could cost the UK economy up to $8.8 billion.

Visit Business Insider's homepage for more stories.

The Trump administration has come out guns blazing to try and get the UK to freeze out Chinese tech giant Huawei.

For over a year now the US has been lobbying its allies to exclude Huawei's 5G telecoms equipment from their networks.

Over the last week the Trump administration has redoubled its efforts to convince the UK to ditch Huawei, and a special US delegation was sent over on Monday told British minsters allowing Huawei to install 5G kit in the UK would be "nothing short of madness," The Guardian reported.

America's fresh offensive on the UK is turning up the heat on Prime Minister Boris Johnson, and one member of the US delegation said "Donald Trump is watching closely."

Last week British Foreign Secretary Dominic Raab also met with Secretary of State Mike Pompeo in Washington, and Huawei was reportedly a topic for discussion.

Previously the US has warned that it would sever intelligence-sharing relationships with allies who continue to use Huawei, although the head of MI5 recently said he didn't see this as much of a threat.

The US claims Huawei poses a national security threat, as it claims the company acts as a proxy for the Chinese government to spy. Huawei denies this.

America's lobbying efforts have been met only partial success. Australia and Japan have excluded Huawei's telecoms, but other major allies like the UK and Germany have stayed quiet.

Huawei's market dominance as a telecoms supplier makes it difficult to rule out, it lays claim to roughly 28% of the market while the next-biggest supplier Nokia only has 16%, according to research from Dell'Oro Group.

Research by telecoms analysts at Assembly also indicated that if the UK froze out Huawei it could delay a full 5G rollout by up to 24 months and cost the UK economy between £4.5 billion ($5.8 billion) and £6.8 billion ($8.8 billion).

The decision puts Johnson in an awkward position. His relationship with the US president may already be on the rocks given Johnson appeared to mock Trump's boastfulness in an interview with the BBC on Tuesday. During the same interview, Johnson said critics of Huawei must come up with an "alternative."

"We are confident that the UK Government will make a decision based upon evidence, as opposed to unsubstantiated allegations," a Huawei spokeswoman said in a statement to Business Insider.

"Two UK parliamentary committees concluded there is no technical reason to ban us from supplying 5G equipment and this week the Head of MI5 said, there is 'no reason to think' the UK's intelligence-sharing relationship with the US would be harmed if Britain continued to use Huawei technology," she added.