The firm said its scheme to offer customers a cash exchange saw 90% of its bottles (pictured) returned to retailers in the early 90s, but this has now dropped to 50%.

Barr has instructed retailers to continue to accept bottles until the 31 December, after which point the firm said it will no longer have the facilities to wash returned bottles.

The company’s commercial director, Jonathan Kemp said: “With improved kerbside recycling, only one in two of our bottles are now being returned, meaning that the process of handling returned bottles has become uneconomic.

“From the beginning of October information on the change will be carried on the bottle label and we will work with retailers to display materials in their premises to ensure our consumers understand what is planned.”

Barr has announced an investment of £5m in its Cumbernauld facility with the installation of a high-speed filling for its glass bottles.

This will replace Barr’s current glass line, almost 20 years old, and will see the returnable glass bottle washing equipment decommissioned.

The company recommended consumers should recycle their bottles through their household recycling scheme or public facilities.

Richard Lochhead sent Truss a copy of a Zero Waste Scotland report, looking at introducing a deposit of between 10p and 20p on the price of all drinks and containers that would be refunded to consumers when returned to a collection point.