Over the weekend Royal Mail revealed plans to hire 30,000 temporary staff over the coming weeks, which sparked an angry response from the Communication Workers Union.
The company normally brings in around 15,000 agency staff to help it cope with the volume of mail before Christmas.
The union claimed that the move could be illegal due to laws that prevent employers and employment agencies using agency staff to break lawful strikes.
Royal Mail claims it is bringing in the temporary workers to deal with mail piled up by potential walkouts as well as handling the Christmas period.
The union has claimed that there will be a backlog of "well over 60 million items" by the weekend as a result of walkouts planned for Thursday and Friday.
Royal Mail's rival TNT Post, which has been trialling its own workforce of orange-uniformed postmen in Liverpool for the past 18 months, today said it would be unlikely to roll out such a service nationally as it was economically unviable.
TNT believes a rollout would not be worth committing to unless the rules on VAT and postal services — which give Royal Mail an exemption from the tax — are reformed. It has taken its complaint to the European Court of Justice.
Communication Workers Union
Royal Mail and union to meet for talks
LONDON - Royal Mail and the postal workers' union are to hold talks today, raising hopes of a peace deal before national walkouts are due to start later this week.