Analysts warned, however, that if temporary security measures virtually eliminating cabin baggage were made permanent, they may prove an issue for the low cost carrier business model, affecting Ryanair, EasyJet and Aer Lingus on its short-haul routes.

But airlines reported returning to business as usual by Saturday morning, with Ryanair and EasyJet expected to have full schedules.

Significantly, both Ryanair and Aer Lingus said on Friday that they had suffered no appreciable drop-off in bookings.

Ryanair shares finished down on the week at 7.24, dropping from 7.55 on Wednesday close, but losses were not as severe as many feared. EasyJet actually posted a 3p gain on Friday in London trading.

Industry observers said it was too soon to tell whether the terror threat would have lasting effects on short or long-haul passenger numbers, something that would only become clear after perhaps four weeks. But they said it would be a test of mettle at management of all airlines.

"Shocks like this really expose strong and weak players in the industry, " said one analyst. After 9/11, the collapse of Sabena and Swissair were as much the result of poor business models as passenger numbers.

Analysts were hopeful that regulators would not over-react to the threat.

"Thankfully, the Brussels gang are all on extended holidays, " quipped Goodbody analyst Joe Gill in a Friday morning note.