A petition to keep the recipe of Irn-Bru the same has hit more than 21,000 signatures.

AG Barr announced the change to sugar content in the fizzy drink ahead of the introduction of a sugar tax.

Ryan Allen took to change.org to call for the alteration to be cancelled.

Mr Allen wrote: "I would far rather pay more for a bottle than have an altered recipe version.

"I believe that a responsible adult should have the choice as to what poisons they want to put in their body and I think that Irn-Bru should continue to sell its original full sugar recipe even if that is at a price increase."

An AG Barr spokesperson said: "From January 2018, Irn-Bru will continue to be made using the same secret Irn-Bru flavour essence but with less sugar.

"The vast majority of our drinkers want to consume less sugar so that's what we're now offering.

"We know that our loyal drinkers love Irn-Bru for its unique great taste and we've worked hard to deliver this."

The spokesperson added: "We ran lots of taste tests that showed most people can't tell the difference - nine out of ten regular Irn-Bru drinkers told us we had a good or excellent taste match.

"Irn-Bru will remain a sugary drink as the sugar in a can will reduce from eight and a half teaspoons to four. A can of Irn-Bru today has just under 140 calories and in the future will have around 65 calories.

"Most shoppers can expect to buy Irn-Bru with reduced sugar from later this month."