The airline currently has more than 400 volunteers working to deal with the baggage mountain and luggage is being sent to a courier firm in Milan where it will be sorted and either driven or flown to owners.

A BA spokesman said: "Delayed bags must undergo enhanced levels of security screening.

"Much of this process must be done manually rather than using the automated baggage systems.

"Although the majority of delayed bags will be sorted and reflighted at Heathrow, we can reunite larger numbers of bags with their owners more quickly.

"It is quicker for bags with European mainland addresses to go to Milan for sorting and onward transport than waiting for space to appear on flights leaving Heathrow."

She said it was standard practice for BA to use the Milan-based courier firm when coping with a backlog.

The same procedure was used last year when baggage problems arose.

British Airways continues to cancel flights from Terminal Five with 50 axed on Tuesday, although the airline says fewer will be affected on Wednesday and 92% will operate on Thursday.