Localised strikes have already caused chaos for small businesses after late delivery of bills have incurred fines and charges.

But now one of Royal Mail's biggest clients, Amazon, has reportedly ditched the national postal service as the parcel backlog continues to build up.

A spokesperson for Amazon says there have been no long term cancellations of its £25m contract with the Royal Mail.

But they are looking at alternative carriers to ensure they maintain their "high standards that customers expect".

The strike threat comes after months of locked horns between the Royal Mail and postal workers over job cuts and pay freezes.