The American embassy has dismissed reports that the US government wants to tighten visa restrictions for British citizens of Pakistani origin.
The fertiliser bomb plot trial has brought the visa waiver into focus
Homeland Security Secretary Michael Chertoff had discussed the plan with London, the New York Times said.
But John Caulfield, the consul general at the embassy in London, told the BBC that the report was wrong.
It follows the conviction of five men, four of them of Pakistani origin, for a UK bomb plot linked to al-Qaeda.
According to the New York Times report, Mr Chertoff had spoken to UK officials about the prospect of forcing British citizens of Pakistani origin to obtain a visa for visits to the US.
Another proposal was cancelling the UK visa waiver programme, requiring more than a million visitors from Britain each year to apply for a visa, the paper said.
But Mr Caulfield told BBC Radio 4's Today programme: "Secretary Chertoff did not make the comments attributed to him.
"The US has not told the British government that we want to exclude Britons of any particular ethnic group."
He added: "We have talked about security continually with Britain and our allies. We are worried about terrorism but he did not make any suggestion that any particular group of Britons should be denied access to the visa waiver programme."
Dr Stefan Halper of the Centre of International Studies at Cambridge told the programme: "Even though the consul general says there is no specific discussion at this point, there is an issue here.
"US security is on the line and the British have a problem of political and cultural sensitivities, particularly ahead of an election," said Dr Halper, who has worked on security issues for four administrations in Washington.
Introducing visa controls for British Pakistanis would cause uproar if it were introduced.
Azzam Tamini of the British Muslim Initiative said it amounted to racism.
"You cannot condemn an entire community for the sins of the few," said Mr Tamini.
The UK Home Office said it would be unacceptable to "single out citizens of any particular background".
A spokeswoman said such plans had not been discussed at a meeting last month between Home Secretary John Reid and Mr Chertoff.
The Foreign Office reiterated that it did not represent UK government policy, and would not be an acceptable proposal.
"It smacks of discrimination," said a spokesman.
He added: "We are in close contact with the US about immigration issues as a matter of course and they are aware of our view that changes to the visa waiver scheme could cause economic damage to both our countries without enhancing security controls."