Thursday, August 10 2006 19:27 Hrs (IST) - World Time -

Washington: The US today (Aug 10, 2006) raised its security level to the highest category 'Red' for commercial flights from Britain in response to an aborted terror plot in Britain.

A statement from the Department of Homeland Security said, "The US government has raised the nation's threat level to Severe, or Red, for commercial flights originating in Britain bound for the US."

Earlier Thursday, the police in London said they had thwarted a major terrorist plot to blow up aircraft in mid-flight.

Scotland Yard said the aim of the plot was to detonate explosive devices on board the aircraft in hand luggage.

The plot was likely to target flights from Britain to the US, it said. Police made a number of arrests overnight in London.

Responding to the incident, Britain raised its security threat level to "critical" from 'severe'.

Britain has a five-level rating for security threats, ranging from low to critical, which is the highest level.

Security at the airports across Britain has been beefed up. A total of 18 people had been arrested so far, according to BBC.