Vinci, the French construction group, is considering whether to pull out of its £517.3 million sterling (€824.65 million) bid for TBI, the regional airports operator. TBI shares fell 10p, or 12 per cent, to 73-1/2p as speculation grew that Vinci would not proceed with its 90p a share bid.

Analysts expect airlines and airport operators to be among the hardest hit from the aftermath of the terrorist attacks in the US, as individuals become more reluctant to fly and the cost of airline and airport security rises. Mr Andrew Murphy, at WestLB Panmure, said he expected to revise down his forecast of TBI's pre-tax profits in the year to March 2002 from the current level of £20.5 million.

TBI said the aftermath of the terrorist attacks did not change the value of the business.

It added that discussions with possible counter-bidders were continuing.

However, analysts said the chances of a white knight emerging were beginning to fade.

The first closing date for Vinci's offer is Monday. Vinci is expected to make a statement then on whether it is proceeding with the bid. It declined to comment ahead of the statement.

However, it is understood that Vinci could either choose to extend the offer, or say that the conditions of the bid have not been met and let the offer lapse.