The only problem, though, is that he cannot promise when this will happen.

Speaking at a Hong Kong General Chamber of Commerce luncheon, Lord Marshall said: 'Clearly we're going to have to live with [enhanced] security forevermore.'

'But hopefully, with improving technology, that will be made simpler and easier. If you fly a lot, it's going to take a long time to implement the new technologies everywhere around the world,' he said.

While acknowledging that the need for passengers to remove their coats and shoes for security checks sometimes made for angry customers, Lord Marshall said the industry was now in an 'interim period' in devising ways to deal with these hassles.

'Technology will help with the check-in process. For us, passengers are already able to print their own boarding passes at home before they arrive at the airport. That will help reduce the long lines,' he said.

'Further on, new technologies may develop that will negate the need to remove your coat and shoes at security checkpoints in airports. If we can do this, then we can keep improving convenience.'

Lord Marshall said the increase in air-rage problems mostly resulted from 'congestion at airports and new security measures that have been introduced very suddenly, especially immigration processes'.

US immigration officials have begun fingerprinting some tourists as part of a programme to track potential terrorists.

Also, the debate over armed air marshals travelling on commercial jetliners is continuing between international airlines and the US government.