British Airways has come under fire over the privacy of passenger information.

Some 2,000 airline staff have access, via iPads, to passenger data in the "Know Me"scheme, which BA argues will create a more efficient and personalised service for customers.

Staff will be able to find out details such as a customer's travel and complaints history, while using Google Images to search for pictures so they can spot a passenger the next time they take a flight. Around 4,500 passengers a day are expected to be greeted personally by staff by the end of the year. But the initiative has been criticised by privacy groups.

Nick Pickles, director of Big Brother Watch, said: "Fundamentally British Airways have not asked their passengers' permission to search Google to find their picture or any other information."

"This goes to show that major international companies now recognise the best way to find out personal information about its customers is to ask Google."

BA defended the scheme, saying it would help staff, for example, to resolve complaints more efficiently.

A spokesman said: "The most recent advancement of the system enables the British Airways team to search Google Images for a photo of specific customers, so they can recognise them as soon as they enter the airport or aircraft and proactively approach them."

BA's head of revenue and customer analysis, Jo Boswell, added: "Solving problems at the point of failure is a lot more powerful than waiting until after the event. It is more powerful when customers don't have to repeat their stories to different departments within BA."

"High-profile travellers' and those who have experienced problems are expected to receive particular attention."

Ms Boswell said the carrier was trying to recreate the "feeling of recognition you get in a favourite restaurant when you're welcomed there, but in our case it will be delivered by thousands of staff to millions of customers."

Data protection watchdog the Information Commissioner's Office said the scheme would need to comply with the law where private data must be held securely and only accessed when needed.

BA's spokesman added: "We are entirely compliant with the UK Data Protection Act and would never breach that.

"'Know Me is simply another tool to enable us to offer good customer service, similar to the recognition that High Street loyalty scheme members expect.

"The Google Images search app helps our customer service team to recognise high-profile travellers such as captains of industry who would be using our first class facilities, enabling us to give a more personalised service."