''We don't wish to cause them any more (aggravation) than we have to,'' he said of the passengers. ''But it's something that has to be done.''
Gate Gourmet, which is undertaking restructuring amid financial losses, said it was trying to resolve the dispute.
The caterer, which is owned by the Fort Worth, Texas, buyout firm Texas Pacific Group, reported a loss of $41.25 million last financial year, and was expecting a $44.84 million loss for the current year.
This is the third consecutive year that BA has suffered a disruption at the height of the summer holiday season. Last August, thousands of disgruntled vacationers were stranded at Heathrow after the airline canceled scores of flights because of staff shortages and technical hitches.
In July 2003, an unofficial walkout by several hundred check-in staff disrupted thousands of passengers and cost BA tens of millions of dollars.
Henk Potts, an analyst at Barclays Stockbrokers, said the latest dispute could cost the airline 10 million pounds ($18 million) a day.
In its last financial year, which ended in March, British Airways PLC earned 251 million pounds ($467.31 million), up from 130 million pounds in the previous year. Full-year revenue rose 3.3 percent to 7.8 billion pounds ($14.49 billion).