Workers at telecoms giant Ericsson's Burgess Hill base could still face redundancy after the firm announced job cuts at two other UK plants.
The company has announced it will shed more than 12,000 of its workforce of 100,000 around the world.
Now the Swedish company hopes to save 1,000 British jobs through the sale of factories in Scunthorpe and Carlton, Nottinghamshire.
But workers at the Burgess Hill plant will not know whether their jobs are safe until the end of June.
A spokesman said: "The factories in Scunthorpe and Carlton are being sold but they manufacture consumer products while the Burgess Hill plant is part of our sales division.
"There could be 10,000 redundancies worldwide and this could still affect jobs in the UK. We should know which areas are going to be affected at the end of June."
Union bosses have had talks with bosses to try to make sure any UK redundancies are voluntary.
They have admitted this is unlikely and employees have been warned to brace themselves for compulsory job losses.
It is thought only a fraction of the cuts will be made at the company's headquarters in Charles Avenue, Burgess Hill, where 500 people work in sales.
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