Britain today raised its international terrorism threat level to 'severe' - its second highest level of terror alert - from 'substantial', home secretary Alan Johnson said.
"The Joint Terrorism Analysis Centre has today raised the threat to the UK from international terrorism from substantial to severe".
"This means that a terrorist attack is highly likely, but I should stress that there is no intelligence to suggest than an attack is imminent," he said in a statement.
Mr Johnson added: “The highest security alert is critical and that means an attack is imminent, and we are not at that level.”
He said more measures had been taken to protect aviation since the alleged failed bomb attack on a plane at Detroit at Christmas.
“We have a very adept and very focused counter-terrorism facility in this country and people should be reassured by that.”
He said that moving to the different threat level meant people had to be more alert, but there was absolutely no intelligence to suggest that an attack was imminent.
Agencies