The current terror threat level has been classed severe - one level lower than the highest "critical" - since 14 August 2006.

BBC: NEWS | UK | Two car bombs found in West End

The terror threat level on the UK Home Office website remains unchanged at "substantial, " which is the third highest of five levels.

CNN: London's Olympic security headache

France increased its domestic terror threat level after French forces went into action in Mali on 11 January to push back militants who had captured Timbuktu and other parts of northern Mali.

BBC: A French soldier patrols a street in Paris, 15 January