LONDON — Bags were painstakingly checked, babies were frisked, and in-flight screens showing a plane's location and flight path had to be switched off.

International airports from South Korea to Paris had ramped up security Monday, causing long queues and inconveniences, after last week's attempted attack aboard a Detroit-bound plane. Airlines managed to keep the disruptions and delays to a minimum, though, by giving many travelers advance warning of the new security measures.

At London's Heathrow Airport, Europe's busiest air hub, small lines built up at departure gates, with flights to the U.S. running about an hour behind schedule. Most passengers, traveling for the holidays, took things in stride.

"It's Christmas as well, so you'd expect some delays," said Mary Lecarpentier, 45, who was flying from London to New York for New Year's celebrations. "I've only just joined this line and it's fine. I'm nearly there."

British Airways was telling customers flying to the U.S. to carry only one item of hand luggage and to expect any gifts they were carrying to be unwrapped at security. Virgin Atlantic posted a similar announcement on its Web site. Both airlines said delays had been minimal.

Officials have given scarce details about the restrictions introduced over the weekend, saying they do not want terrorists to know about security measures after a man aboard a Northwest Airlines flight Friday from Nigeria through Amsterdam to Detroit, Mich., tried to ignite an explosive as the plane prepared to land.

For 24-year-old Sylwia Cieplak, who was returning to Milan from Poland, the attempted Christmas-Day attack only intensified her fear of flying. "I really hope there will be more security on my flight," she said. "They can check everything; that's no problem for me."