US police received intelligence reports two weeks ago that warned of a possible attack in Glasgow against "airport infrastructure or aircraft", according to reports.
An unnamed official told ABC News the intelligence led to the assignment of 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 but said 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-Qaeda-connected terrorists, ABC News said.
Similar warnings last month led to air marshals being deployed on flights into and out of Germany.
Strathclyde Police chief constable Willie Rae said his force had been given no warning of Saturday's Glasgow airport attack.
