Post Office bosses have denied setting a date for the closure of Eastbourne's main branch.
Posters were put up by staff at the office in Upperton Road over the weekend saying the branch would close on February 14.
But representatives from the Post Office say no firm decision has yet been taken, in light of recent consultations with town politicians and the public.
A spokesman for the company said it would be several weeks until a verdict was announced over the future of the branch.
Ian Ward, of the Communication Workers Union, which represents postal workers, said although staff had been acting on a rumour he feared an official announcement would soon follow.
He said: "The Post Office feels that by adding an extra three serving positions the Terminus Road branch will be equipped to take the workload for postal services in this area.
"I don't know how they will even get the serving positions in there and even if they can, it won't be enough."
The branch was earmarked for closure after Post Office bosses announced it was losing thousands of pounds each year.
A high-profile campaign was launched resulting in thousands of people signing a petition, which was handed over to Post Office bosses earlier this month.
Three other town sub-post offices are also to close as part of a shake-up to the postal service.
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