Up to 650 Sussex workers have been told they must move to Luton or risk losing their jobs following a multimillion pound merger.

The staff face redundancy from TUI Travel in Crawley.

The German company merged the popular Thomson and First Choice travel brands last year.

It now plans to close its flagship First Choice House base in London Road, Crawley, in an attempt to streamline operations and make annual savings of £150 million.

Staff have been told they can relocate or leave before the office closes next year.

They were informed of the decision to move their jobs to Thomson's offices in Bedfordshire when they returned to work after the new year.

The company also runs four other offices in the Crawley area, where staff hope their jobs will be safe.

A corporate team from First Choice House has already been transferred to nearby TUI Travel House in Fleming Way.

A spokeswoman said Eastman House in London Road was "still fully staffed with no plans to close", while specialist business operators at The Atrium, London Road, and staff at Jet Set House in Lowfield Heath, near Gatwick, remained unaffected by the plans.

However, workers at First Choice House face a year of uncertainty.

It is not thought they are collectively represented by a trade union.

The spokeswoman added: "We began a formal consultation with staff about the First Choice House relocation in September.

Staff were told in the first week of the new year that it would definitely happen.

"In the vast majority of cases people have been given alternative roles in Luton.

We've still got the building until the end of 2009 so this is going to happen gradually.

"The company is doing its best to be flexible in its approach, allowing some people to work in both Luton and at home.

"I can imagine some people will instead choose, for various personal reasons, to take redundancy."

The news came as TUI announced plans to close about 100 high street stores.

The closures of Thomson and First Choice shops will contribute to £150 million of annual savings the firm is expecting to make following its merger - 50 per cent more than its original calculations.

It will affect almost ten per cent of the Thomson and First Choice high street network of about 1,100 stores.

Peter Long, TUI's chief executive, refused to give a total number of job losses, saying the matter was "sensitive" and the company was still in consultation.

However, he said: "Clearly it's not small numbers but we want to achieve a lot of this through natural reductions."

The company employs about 19,000 staff in Britain.

Mr Long added that the company was performing well and had not been affected by the fall in consumer confidence because people were not sacrificing holidays to save money.

TUI has more than 200 travel companies on its books, including its Skiing and Schools Abroad offices, based in Marine Parade, Brighton. These will not be affected by the changes.

andy.dickenson@theargus.co.uk