Six hundred people work at the Coventry sorting office

Royal Mail wants to move the Bishop Street centre, where 600 people work, to a new site in Northamptonshire.

But protesters, organised by the Commercial Workers Union (CWU), gathered in Millennium Square to demonstrate their opposition.

Royal Mail has said it does not know the exact location of the new centre or when the move would take place.

'Jobs displaced'

Des Arthur, of the CWU, said: "Royal Mail project managers are to put their closure proposals to the Royal Mail Board in early April 2007.

"We have until then to demonstrate to Royal Mail that the closure of Coventry Mail Centre is a mistake.

"If their plans go ahead then by 2009 approximately 600 jobs will be displaced as there will no longer be any mail sorting work done in Coventry."

He added that the union believed Royal Mail would not be able to offer all of the displaced staff alternative employment.

Bob Ainsworth, MP for Coventry North East, said the move would result in a poorer service for people in the city.