Berlin, August 16:

As British airports struggled to return to normal after last week’s dramatic terror alert, the travel and airline industries have begun counting the cost of the delays and cancellations that followed the allegations of a plot to blow up trans-Atlantic jetliners.

Almost 2,500 flights have been cancelled at London’s three principal airports since last Thursday when revelations about the scheme plunged air travel in Britain into chaos and triggered a security clampdown across the global aviation sector.

The upheaval which followed the news that British police were holding more than 20 suspects in connection with the plot is estimated to have cost major British carriers alone about $475 million.

While industry draws up battle plans for business travellers to cope with a new era of strict airport security, the prospects of airlines facing an additional cost burden has raised questions about the future of Europe’s budget airlines, which have emerged as major competitors to scheduled carriers.

The new terror alarm and the moves to dramatically beef up airport and airline security comes at a time when the aviation business has been battling intense competition, soaring fuel prices and a recent round of scares from terrorism through to bird flu.

In a radio interview, Michael O’Leary, the chief of Europe’s leading budget airline, Ryanair Holdings PLC, described the fallout from the terror scare as “almost the breakdown of London airports”.

In the long term, analysts also say the risk for the airline business is that travellers will be put off flying by the tough security measures and the threat of long queues and more specially avoid the various airlines that appear to have become likely terrorist targets.

The possible new carry-on luggage restrictions have raised questions about how laptops and mobile phones, which now form a key part of business travel, can be transported in future scares.

The new security measures have led to doubts about the prospects for Europe’s budget airlines.

Analysts say the network of no-frills carriers could be forced to face the difficult choice of passing any additional costs for security on to the flying public through higher fares or drastically cut their earnings.