British Airways canceled all long and short-haul flights due to depart from London's Heathrow Airport Thursday and diverted arriving flights, after a labor dispute escalated.

The airline said flights would remain grounded until at least Friday evening and estimated 70,000 passengers would be affected. British Airways has about 550 flights a day in and out of Heathrow, its main hub, carrying about 100,000 passengers.

Sixty-two short-haul and 44 long-haul outbound flights, due to depart from Heathrow were canceled Thursday, a further 14 short-haul flights and an unknown number of long-haul flights which were en route to Heathrow were diverted to other airports in Britain. Other flights bound for London were canceled before taking off.

British Airways has six flights daily into Washington Dulles International Airport and two daily flights into Baltimore-Washington International Airport, according to an airline spokesman John Lampl. The airline has contacted passengers by e-mail and telephone to warn of the disruption, he said.

The cancellations were announced after British Airways employees joined a labor dispute between the airline's caterer Gate Gourmet Inc. and its workforce. A union representing Gate Gourmet said the company had fired 800 workers on Wednesday. The company said only 667 workers had been dismissed.

British Airways employees, including baggage handlers represented by the same union, stopped work Thursday in sympathy with the catering staff. Later Thursday, another union representing check-in workers advised its members to stop work for safety reasons after disgruntled passengers took out their frustrations on staff.

Washington Post staff writer Keith Alexander contributed to this report.

A passenger looks at a British Airways plane at London's Heathrow Airport. A labor dispute caused the airline to cancel at least 30 flights.