Loretta Worters, spokesperson for the Insurance Information Institute (I.I.I.), noted, "In terms of business interruption for the airports, there would be none because there is no physical damage to the airport or planes. So certainly this will be a financial setback for the airlines."

Mr. Woo yesterday also said aviation and travel insurers will be hit by the cost of several days of flight cancellations.

Mr. Allan today said, however, "Successful claims against standard airline liability insurance policies due to delays as a result of the volcanic eruption in Iceland are unlikely. This is a natural event and there has not been any actual damage to aircraft or property at this stage."

For travel insurance, coverage would depend on the policy, according to Ms. Worters. "Travel insurance policies will differ in this situation; there is no standard set of conditions which applies to a situation of this kind," she said, "Therefore customers should check their travel insurance policy, and speak to their travel insurer to understand what their individual policy covers them for in this situation."

Volcanic eruptions, she said, are not always covered by travel insurance for cancellation or delay, but some policies will cover it, Ms. Worters added.

She said that if a flight is cancelled, most airlines will offer either a full refund or an alternate flight, and if the flight is cancelled and the insured does not travel, most travel insurers will refund the premium if it is a single trip policy.

Travel insurers also will usually amend a policy to cover new travel arrangements and dates, Ms. Worters said.