Tighter security measures ordered after the bombing of Pan Am Flight 103 took effect Friday at British airports, causing some passenger delays while workers closely searched carry-on baggage.

Transport Secretary Paul Channon announced the stepped-up security Thursday after a meeting of the National Aviation Security Committee in London.The new measures are aimed primarily at American carriers, and passengers faced long lines to have their hand baggage examined before boarding Pan Am and TWA flights at London's Heathrow Airport.

"I certainly believe that it's best to take a few extra precuations and be safe, rather than rush things and be sorry," said Lee Godman of Miami.