British police yesterday said they had thwarted a plot to blow up planes in mid-flight between Britain and the United States and were holding 21 people.
The British Airports Authority said it had asked all European carriers to suspend flights to London's main Heathrow airport, where beefed-up security caused severe delays.
Here is a list of some recent British aviation security alerts:
December 22, 2001 - Airports around the world were on high alert after "shoe bomber" Richard Reid was caught apparently trying to blow up an American Airlines plane from Paris to Miami with explosives hidden in his shoes.
February 13, 2003 - Parts of Gatwick airport were evacuated and flights suspended after a grenade was discovered during a random X-ray check. A depressed Venezuelan man had smuggled the grenade on to a London-bound plane to blow himself up to highlight humanitarian causes. He received a six-year prison sentence.
September 13 - Gatwick was partially evacuated after an apparently abandoned vehicle was found near the airport. Bomb disposal experts carried out controlled explosions on the vehicle but found nothing suspicious.
January/February 2004 - British Airways cancelled several flights to the United States and Saudi Arabia after terrorism alerts. Security was stepped up at Heathrow Airport.
September 23, 2005 - Parts of two terminals were evacuated and closed for a few hours at Manchester Airport after a security alert sparked by the arrest of a man carrying a suspicious package near an aircraft. The man was found to be mentally ill.
December 12 - A British businessman who said he had a bomb in his bag while waiting for a flight at Scotland's Inverness airport set off an alert and led to the evacuation of the flight's 124 passengers. He was sentenced to two months in jail.
April 12 - A Ryanair flight from Paris to Dublin was diverted to Glasgow's Prestwick Airport after a hoax bomb alert. A huge security operation caused widespread disruption to flights to and from the airport.
August 7, 2006 - A Boston-bound American Airlines plane with 240 passengers and 13 crew turned back to London's Heathrow airport in mid-flight after it was found that the name of a passenger on the plane matched that on a US"no-fly" list.