US law enforcement officials received intelligence reports two weeks ago which warned of a possible terror attack in Glasgow against "airport infrastructure or aircraft", according to reports.
An unnamed senior official told ABC News the intelligence led to the assignment of Federal Air Marshals to flights into and out of both Glasgow and Prague in the Czech Republic.
US Homeland Security Secretary Michael Chertoff declined to comment on the report, but on Monday told ABC News that "everything that we get is shared virtually instantaneously with our counterparts in Britain and vice versa".
The intelligence reports also warned that airports and aircraft in the Czech Republic could be the targets of al Qaida-connected terrorists, ABC News said.
Similar warnings last month led to air marshals being deployed on flights into and out of Germany.
Mr Chertoff said US authorities were "in close contact" with their counterparts in the UK at the weekend.
He said he had "seen no specific, credible information suggesting that this latest incident is connected to a threat to the homeland".
Mr Chertoff said security measures at US airports, mass transit and other transportation facilities would be increased ahead of the US Independence Day holiday on Wednesday.
"Some of these measures will be visible; others will not," he said.
Strathclyde Police chief constable Willie Rae said his force had been given no prior warning of Saturday's Glasgow Airport attack.
