Small companies have £2.5m worth of business delayed every time there is a postal strike, according to figures produced by the British Chambers of Commerce.

Using information from industry regulator Postcomm, the BCC has worked out that the amount of post sent out by small firms through franking machines ranges from £1.8m to £2.6m every day, depending on whether mail is sent first or second class.

“Most smaller sized businesses have no option but to use Royal Mail and collectively spend millions of pounds each day on their post,” said Natalie Evans, head of policy at the British Chambers of Commerce. “This series of strikes is doing nothing but cause delay and frustration for those who rely on the postal service and the sooner it is resolved the better.”

The Communication Workers Union has called a series of strikes and rolling walk-out periods aimed at maximising disruption to Royal Mail in a battle over pay and modernisation reforms.