A 5% slump in value sales of Magners cider in the UK is a warning to other brands of the dangers of multi-pack special offers, according to industry insiders.

Magners owner C&C Group admitted that a 9% rise in UK volume sales of the brand was the result of substantial promotional activity and that its margins had "been negatively impacted" by the lower prices.

Such activity was damaging the cider category as a whole, added industry experts. Selling multi-packs at less than £10 for two cases increased footfall and volume sales - but

produced almost no margins and could threaten premium brands' higher pricing, they warned.

"Companies are trying to sell volumes by any means necessary, but if prices drop much lower to do this, margins may never recover," said one.

Another added: "Such deals are tainting the value of the category."