The British public is being warned to be extra vigilant and report suspicious activity after the country raised its terror threat alert level.
Less than a month after an attempt to blow up a US-bound flight from Europe, London has raised its threat level from substantial to severe.
This means a terrrorist attack is considered to be highly likely. The level had remained on “substantial” since last July.
British Home Secretary Alan Johnson said: “We know this country faces a threat from international terrorism. The fact that we have gone to a different level in respect of that threat is part of the system of protecting the public against that threat.”
London is not talking about any specific threat, but says several factors are used to raise the alert levels.
It went up to critical in August 2006 when three men were accused of plotting to target UK flights with liquid explosives.
It also went up to critical in June 2007 after attempted car bombings in London and Glasgow.
Other new anti-terrorist measures in Britain include boosted security checks and the drawing up of a US-style “no fly” list.
It is also reported that British police are planning to use unmanned spy drones for surveillance by 2012.