British Airways is to close call centres in Glasgow and London and move 400 jobs, the airline has announced.
The airline said it was receiving fewer booking calls
The centre in Glasgow, which employs 350 people, will shut by November, while a site in London where 50 people work will close next March.
BA said that almost 400 jobs would be created at the airline's call centres in Manchester, Newcastle and Belfast.
The firm said the move was in response to the increased number of people making bookings online.
Telephone calls to the airline's five call centres in the UK have fallen by 34% in the last two years, from 13 million to 8.5 million a year.
The airline has also reduced the number of staff employed in its UK call centre
operation by 900 since 2001.
Pat Gaffey, head of British Airways Global Direct, said: "This difference between the amount of property we have in the UK and the number of employees we now have means we cannot afford, in our current financial position, to retain property which is not supporting the business.
"We intend to close Glasgow as we have, due to our lease terms, an imminent opportunity to leave the current building with minimal exit costs.
"It is not based on the performance of our people in Glasgow. We will be offering our people in Glasgow and London every support going forward.
"This decision is not about moving work or calls abroad and customers in the UK will still speak to operators based in our UK call centres."
Scotland's Deputy Enterprise Minister Lewis Macdonald said he was "extremely disappointed" as Glasgow had proved to be a flagship operation.
He said: "This will be a severe blow to the 350 employees on the site.
"Jim Wallace (Enterprise Minister) and I have had discussions with BA senior management in recent weeks to put forward options for retaining these functions in Scotland.
Lewis Macdonald said talks to save the Glasgow centre failed
"Despite these efforts, BA has announced its intention to close the Glasgow operation in November 2004."
Mr Macdonald said there would be a formal consultation period and a meeting with the company to discuss the best outcome for the workers involved.
The GMB union said the announcement was "devastating news" and vowed to fight the closure of the Glasgow centre, where it represents workers.
National officer Allen Black said: "The majority of the workforce in Glasgow live in an area of high unemployment and, not only is this devastating news for them, it is also a blow to the local economy.
"We will be asking BA to bring in-house work that is currently being done both in the UK and abroad to ensure that our members' jobs are safeguarded."
The Transport and General Workers Union claimed the closures were premature and called on BA to "properly review the functions and locations with the full involvement of the workforces concerned".
Scottish National Party Leader John Swinney said the news was "a massive blow" to workers.
He said: "The Scottish Executive claims that building the economy is one of its top priorities, but all we have seen so far is Scotland losing jobs hand over fist to other parts of the UK.
"Scotland has just lost over 500 jobs in a matter of hours and it's time for the executive to make a serious commitment to securing employment across the country."