The US State Department says Al-Qaeda is planning a major terror attack somewhere in Europe.
It has warned its nationals to be vigilant when travelling across the continent and to take care in busy tourist areas. Britain, France and Germany are believed to be the countries that the militants are targeting.
The UK has also upgraded its travel advice for British citizens travelling to France and Germany. The Foreign Office says there is a “high threat” of a terrorist attack in those two countries.
The plot is believed to involve British citizens of Pakistani origin and German citizens of Afghan origin.
No arrests have yet been made although security sources say a number of individuals are under surveillance.