Transatlantic airline passengers face queuing for almost five hours to check in because of new security measures.

People flying to the US from Gatwick and other British airports could have to check in for flights much earlier when the system is introduced, possibly this summer.

American authorities will require detailed information such as the address of a first night's stay and passengers' visa details.

The Association of British Travel Agents said processing could add more than two hours to check-in times, already about two hours.

The move is part of tightened security following the September 11 attacks.

Only flights to the States would be affected at first, although Canada and South Africa are thought to be considering the same system.

Charter airlines, which do not yet have the technology needed to transfer the information, are expected to suffer most delays.

Airport operator BAA said there had been no clear direction from US authorities about the new system and it could not speculate when it would be introduced or what the implications would be.

A spokeswoman said security was a top priority but there were concerns about longer check-in times.

She said: "We will continue to monitor this and any implications it may have for people travelling through airports."