As the crisis in the Persian Gulf intensifies, a fear of terrorism is causing tour groups to postpone trips, business travelers to curtail out-of-town meetings, airlines to cancel flights and leisure travelers to forgo vacations abroad.

Over the past week, many travel agents said they have been overwhelmed by calls from customers who want to either change their plans or gather more information about the potential dangers of flying while the country is at war with Iraq. As a result, bookings are falling off, primarily for international travel and to some extent for domestic trips.

On the East Coast particularly, people are changing their plans as they react to news of the war or follow the directives of their companies not to travel.

"We polled all our offices," said Daniel Bohan, vice president of Omega World Travel in Falls Church, "and the only places being hard hit are in the Washington-New York corridor."

Federal officials last week said they had seen "no credible threat" by terrorists to the Washington area. Despite that, Bohan said, "Mr. Saddam has been very successful in terrorizing people in the Washington and New York metropolitan areas."

Omega, one of the country's largest travel agencies with 150 offices nationwide, estimated that bookings are off 75 percent to Europe and Africa. Domestic travel has been chilled too, Bohan said, with bookings down 10 percent to 15 percent in some areas.

The falloff in travel is also sending a tremor through the local hotel business.

At the Hay-Adams Hotel, just a block from the White House, there have been 168 cancellations since Jan. 16, "mostly on fears of terrorism," said William Trimble, general manager of the hotel. He said the presence of protesters has brought complaints from many guests. "We are tracking this every day. It's depressing to watch occupancy evaporating," he said.

Firm statistics are not yet available on precisely how much travel is down, but several carriers and other industry observers said they are certain to show a decline.

"Bookings are way, way off," said Robert J. Aronson, head of the Air Transport Association, which represents most major U.S. airlines. The decline in traffic began with the recession, but "it's much more {a matter of} war jitters at the moment," he said.

A spokesman for American Airlines said international flights typically are more than 50 percent full at this time of the year. But since the war began, only about one-third of the seats have been taken, he said.

Flights to Europe are so poorly booked that Trans World Airlines earlier this week was forced to cancel half its European flights, and yesterday Spain's national carrier, Iberia SA, announced it would reduce flights between New York and Barcelona.

To accommodate travelers, several carriers have adopted more lenient policies about changing plans without penalty.

Conference planners and civic promoters are worried that Washington could be particularly hurt since much of its tourist trade is international. Next week, the D.C. Committee to Promote Washington, a local government agency, will meet to assess how the war is affecting people's travel plans to Washington.

"I hope it all calms, since we are now marketing heavily ... to the Japanese and Germans, and if they are scared to come, it will affect things here a lot," said Deidre Daly, director of the committee.

Government, business and leisure travelers were reportedly changing plans almost as quickly as news was coming in from the gulf. International Business Machines Corp. has restricted travel to certain spots around the world where it thinks security might be a concern.

On Sunday, the White House told heads of executive departments and agencies that government employees headed abroad should first "obtain specific country clearances" from the State Department. Earlier, government personnel had been asked to defer travel to the "Near East and South Asian posts."

The impact is also being felt at agencies such as the Commerce Department, which canceled the trips of senior officials stationed in North Africa, the Middle East and South Asia to a meeting in New Delhi.

All of this has delivered a walloping blow to businesses involved in any phase of domestic and international travel.

Omega's Bohan said commissions at the company's Fair Oaks office plummeted to one-third of their normal levels in the last two weeks. Some of the decline is due to the closing of major retailers near the mall, but some is war jitters, he said.

Peter Sontag, chairman and chief executive of USTravel Systems Inc. in Rockville, said foreign travel out of Washington, New York and Houston is off as much as 40 percent.

But even with extra precautions at airports and by airlines, some people still won't fly.

One woman, for example, decided to extend her visit to Washington rather than make a return trip home to North Dakota.

"It's crazy. Who's going to bomb a plane going to North Dakota?" asked Bohan. "God forbid, what would happen if we really had a terrorist incident?"

One frequent business traveler who took the Pan Am Shuttle from Washington to New York yesterday said the return trip was far from full.

But Super Bowl fans have not been deterred. One tour group operator that sets up sports travel packages said, "Our sales have not been affected at all."

There is one change: Buses bound for Tampa Stadium will leave 90 minutes early to allow for tight security.

Staff writers Kara Swisher and Stuart Auerbach contributed to this report.