British Airways is to restructure part of its UK direct sales operation as a result of changing customer behaviour and increased website sales.
It plans to close its call centre in Belfast - which employs 100 people - and all 17 of its UK Travel Shops, by August, affecting a further 300 staff.
The company said one of the main reasons for the move was that more people were booking online.
The airline said it would consult with the affected staff and their unions.
It said it would offer all the support it could to affected staff, either to find other jobs within BA or with other employers.
Since 2001 there has been a fall of 9 million calls to its call centres, it said.
BA will still use call centres, but the work from Northern Ireland will now go to Newcastle and Manchester.
Martin George, British Airways' commercial director, said the company had to reflect how customers were booking flights.
"It is clear that increasing numbers of our customers want to book and organise their travel plans with British Airways via the internet," he said.
"This is a travel industry-wide trend and we have to ensure that our business reflects this."
He said that despite closing BA's call centres in Glasgow and London in 2004 there was still "too much property for the size of our operation".
The airline has seven travel shops in the London area and others in Belfast, Manchester, Birmingham, Glasgow, Edinburgh, Aberdeen, Windsor, Cambridge, Tunbridge Wells and Norwich.
He said that the high street travel shop business was forecast "to make ever increasing losses in the years ahead".
"This decision is not a reflection on the professionalism and efforts of our staff in these areas," he said.
"It is about ensuring that we respond to changes in the marketplace."