Postal workers at a Royal Mail depot in Bristol held a meeting this morning, and will be sent ballot papers to decide if they will go on strike.
Workers at the Mead Street office in Bedminster say they've ended up with a backlog of deliveries.
Royal Mail blamed high levels of sickness for the backlog.
David Wilshire from the Communication Workers Union (CWU) says the Christmas post could be affected:
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Heavy showers overnight, hail and thunder possible, humid
Heavy showers overnight, humid, thunder possible
The Maltings shopping centre was closed to the public after a small amount of the Novichok substance was found in the area.