BA was battered by a strike by check-in staff in mid-July

Check-in and baggage systems were disrupted, particularly at Heathrow where 11 flights were cancelled. BA said there had been only minimal impact at other airports.

The effects of the problem are expected to continue until Sunday morning.

BA said computer systems were disrupted after a problem within the hub of their setup, based near Heathrow, led to a power outage at 0645 BST. Things were back up and running at 0850 BST.

The problem has mainly affected flights out of Heathrow Terminal One. Flights were cancelled and European and domestic services from the airport experienced delays of up to two hours.

BA advised customers to check in as normal and said IT experts were investigating the cause of the problem.

The problem showed up in pockets at different airports across the world and varied from place to place, BA said.

Patchy problem

Passengers at Gatwick have been delayed by about 15 minutes.

Other passengers may find they have taken off without their luggage on board, a spokeswoman said.

In Scottish airports, check-ins were being processed manually before the problem was resolved.

Linda Dobson, trying to fly to Skopje in Macedonia from Heathrow on business, complained that she had waited in a three-hour queue to check in.

"There was no information while we were in the queue whatsoever.

"I flew with BA earlier in the year and there were delays then too. It really does put you off BA."