The US government is considering warning its citizens to stay away from crowded places in Europe because of the threat of an al-Qaeda commando-style attack, the BBC has learned.
US and UK officials have confirmed that updated guidance may be issued because of the current terror threat.
A UK official said the travel advisory would not be country-specific.
It would also not go as far as advising against travel to Europe, the official said.
The advisory will be issued in response to intelligence on an al-Qaeda plan to assemble teams of gunmen and send them into crowded places to kill western civilians.
Officials said the plan was detected in its early stages and that several individuals were still under surveillance.
The suspects include British citizens of Pakistani and German citizens of Afghan origin.
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