THE threat to the UK from international terrorism was tonight raised from substantial to severe - meaning an attack is "highly likely".

Home Secretary Alan Johnson said although the threat had increased there was no intelligence to suggest an attack was imminent.

He 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.

"JTAC keeps the threat level under constant review and makes its judgments based on a broad range of factors, including the intent and capabilities of international terrorist groups in the UK and overseas."