London, May 30 (IANS): British Airways (BA) on Tuesday started operating a full flight schedule after an IT failure saw the airline cancel thousands of flights over the bank holiday weekend, the media reported.

"Our IT systems are now back up and running and we will be operating a full flight schedule at Heathrow and Gatwick," the airline said early on Tuesday.

But it warned it "may take some time" to reunite travellers with their bags, reports the BBC.

BA chief executive Alex Cruz blamed a power surge for the disruption which affected 75,000 people.

"There was a power surge and there was a back-up system which did not work at that particular point in time," Cruz told the BBC.

"It was restored after a few hours in terms of some hardware changes... we will make sure that it doesn't happen again."

He said the failure affected "all the operating of our systems -- baggage, operations, power processing".

BA is liable to reimburse thousands of passengers for refreshments and hotel expenses, and travel industry commentators have suggested the cost to the company -- part of Europe's largest airline group IAG -- could run into tens of millions of pounds.

Shares in IAG, which is listed in both London and Madrid, fell 2.8 per cent in Spain on Monday and are expected to fall again in London trading when it reopens after the bank holiday.