Christmas postal deliveries in London could be hit if union members vote to take industrial action over pay.
The Communication Workers Union (CWU) is calling for strikes in a row over overtime needed to clear the increase in post in the run-up to the festive holidays.
The union also claimed workers were being forced to work on their days off. A spokesman said: “Everyone knows our members will be weighed down like pack mules this Christmas, but Royal Mail is not willing to pay the rate for delivering the work.
“Unfortunately, it looks like we’re heading for very serious problems over Christmas.”
The Royal Mail said the CWU was asking for extra pay for overtime that may not be needed.