Continental Airlines has expanded its paperless boarding pass system to Heathrow, becoming the first carrier to offer the service on UK - US flights.

The airline, which debuted the technology on transatlantic flights from Germany's Frankfurt Airport in December, says that passengers will no longer need a paper printed pass and will instead be able to show their phone or PDA to security and check-in officials. Mobile boarding passes display a two-dimensional bar code along with passenger and flight information, which cannot be manipulated or duplicated.

"We are pleased to add Heathrow to the growing list of airports we serve with mobile boarding passes," said Continental's Martin Hand. "Customers have told us this is the type of product improvement they want, and we will continue to expand the self-service technology to more of our domestic and international destinations."

Paperless or "mobile" boarding passes are regularly used for internal US flights but have been slower to take off internationally due to security and technology requirements. However, a growing number of airlines such as American Airlines and Air Canada have released apps that feature the technology. Industry body IATA (the International Air Transport Association) is pushing for global adoption of the standard.