CRAWLEY, England (Bloomberg)—The volcanic ash cloud that shut down U.K. airspace for six days last month may have cost the travel industry more than £1 billion ($1.5 billion), according to Peter Long, head of tour operator TUI Travel P.L.C.

TUI, Europe’s largest tourism company, said Tuesday that operating profit will be reduced by about £90 million ($133.2 million) because of canceled vacations, as well as the cost of looking after stranded customers and getting them home. Also Tuesday, EasyJet P.L.C., Europe’s second-biggest discount airline, said the disruption to flights cost it £50 million to £75 million ($74.0 million to $111.0 million).

A shutdown of European airspace last month because of ash from Iceland’s Eyjafjallajökull volcano grounded more than 100,000 flights and cost carriers $1.7 billion in lost sales, according to the International Air Transport Assn. The crisis was more damaging to the industry than the Sept. 11, 2001, terror attacks on New York, according to Mr. Long, TUI Travel’s chief executive officer, who said travel companies plan to seek government compensation.

“We had 143 aircraft on the ground doing nothing, meaning a huge number of cancellations,” Mr. Long said in an interview. Still, bookings have improved this month. “We’ve seen a quick recovery in demand—this has not spooked our customers.”

The volcanic ash cloud led to a 21% drop in the number of flights handled by U.K. airports in April, BAA Ltd., the owner of London’s Heathrow airport, said yesterday.

Mr. Long said it would be “appropriate” for the industry to receive state support to help it through the crisis.

“The government has to be an insurer of last resort here,” he said. TUI Travel is working jointly with other tour operators and airlines in talks with governments, the CEO said.

Future disruption to flights should be “substantially” reduced after the introduction by aviation authorities of a three-level system that allows planes to fly where the level of dust in the air is “not a concern,” Mr. Long said.