US Secretary of State Mike Pompeo has met Boris Johnson in Downing Street for “candid” talks on a range of security and economic issues, including China.
Chinese involvement in the UK’s 5G network were among issues discussed.
The UK is under pressure from the US to take swifter action over Huawei, after agreeing to strip the Chinese firm of any role in its 5G rollout from 2027.
No 10 said Boris Johnson had also raised the death of Harry Dunn and the need for “justice” for his family.
The UK continues to seek the extradition of Anne Sacoolas in connection with the 19 year-old’s death in a road traffic collision outside a US military base in Northamptonshire last year.
The US has said it cannot allow Ms Sacoolas, who has been accused of causing Harry Dunn’s death by dangerous driving, to return to the UK to be questioned, insisting she has diplomatic immunity.
In a statement, Downing Street said the PM had made Mr Pompeo aware of the “strong feeling among the people of the UK that justice must be delivered”.
“The prime minister reiterated the need for justice to be done for Harry Dunn and his family,” it said.
Mr Pompeo posted a message on Twitter saying the talks with Mr Johnson and Foreign Secretary Dominic Raab had been “constructive”.
“Our two countries’ long-standing, strong bilateral relationship has laid the foundation for today’s candid discussion on issues ranging from 5G telecommunication to our negotiations for a US-UK free trade agreement.”
Amid opposition from Washington and within the Conservative Party, the government last week reversed its position on giving Huawei a key role in the UK’s next-generation mobile communications network.
Instead, the UK is to ban domestic mobile providers from buying new Huawei 5G equipment after the end of this year and force them to remove all of its 5G kit from their networks by 2027.
Last week, Mr Pompeo signalled that he hoped the UK would act more swiftly and potentially review its whole commercial relationship with the firm.
The US has imposed visa restrictions on staff working for Huawei, which it accuses of spying and providing “material support” to regimes engaging in human rights violations.
The US, Australia and New Zealand – which along with the UK and Canada are members of the five eyes intelligence alliance – have either banned or restricted Huawei from their 5G networks.
The UK has said it will look to other technology suppliers to fill the gap amid concerns that, without Huawei’s expertise and experience, 5G will be delayed and prove much more expensive.
No 10 said Mr Johnson and Mr Pompeo had “discussed the importance of five eyes countries taking an ambitious approach to working together on the technologies of the future”.
Downing Street said the two men also spoke about “shared global security and foreign policy issues, including China’s actions in Hong Kong and Xinjiang, the situation in Iran and the Middle East peace process”.
The two-day visit is likely to be Mr Pompeo’s last to the UK before November’s presidential election.