British Airways passengers faced more delays today after the airline warned them to prepare for hold-ups of up to 48 hours for their flights.

The delays have been caused by huge backlog of flights after two days of industrial action by check-in staff.

More than 360 flights were scrapped across three terminals at Heathrow on Saturday on one of the busiest weekends of the year.

BA check-in staff sparked the chaos by staging a second unofficial walkout over possible changes to working practices.

BA issued a statement which said: "Flights from Heathrow are beginning to return to normal.

"All customers booked to travel on BA flights are advised to go to the airport as normal. The airline is planning to operate the majority of its services but for the very latest information we advise passengers to log on to www.ba.com "Passengers who were booked on services which have been cancelled during the past two days are asked not to travel to the airport today to rebook their flights but to call the airline's reservation line on 0870 8509850 or the special customer helpline number on 0800 727800."

Mike Street, director of customer service and operations, said: "We are extremely sorry for the inconvenience caused to everyone booked on our flights in the past two days."