The United States wants to keep the technology company out of sensitive infrastructure programmes (Picture: PA).
US Secretary of State Mike Pompeo is expected to warn Theresa May over plans to involve Chinese tech giant Huawei in the UK's 5G telecoms network when he meets the Prime Minister for talks in Downing Street.
Mr Pompeo is the first member of US President Donald Trump's administration to speak face-to-face with the PM and Foreign Secretary Jeremy Hunt since last month's National Security Council (NSC) agreed to consider Huawei's involvement.
Washington is urging allies to keep Huawei out of sensitive infrastructure programmes, citing fears that the company may provide a route for China to spy on the West.
Mrs May reportedly gave the green light to the company bidding for work on "non-core" aspects of the hi-tech 5G network at the NSC meeting.
The decision overruled concerns from ministers including Gavin Williamson, who was later sacked as defence secretary over suspicions he was responsible for leaking details from the NSC meeting to a newspaper.
Mr Williamson "strenuously" denies being behind the leak.
Mike Pompeo warned earlier this year that the US will not "partner" with countries that adopt Huawei systems.
"We've made clear that if the risk exceeds the threshold for the United States, we simply won't be able to share [sensitive] information any longer," he said last month.
In talks at 10 Downing Street, Mr Pompeo is also expected to step up US pressure on the UK to isolate Iran.
He made a surprise visit to Iraq immediately before his trip to London, assuring Baghdad that the US opposes other states "interfering in their country" and stands ready "to ensure that Iraq is a sovereign, independent nation".
Mr Trump last year unilaterally pulled the US out of an international nuclear deal with Iran, but the UK and other European powers have refused to follow his lead.
Tensions have escalated in recent days as Washington deployed the aircraft carrier USS Abraham Lincoln to the Gulf.
Mr Trump's national security adviser John Bolton said the move sent "a clear and unmistakable message to the Iranian regime that any attack on United States interest or on those of our allies will be met with unrelenting force".