A storm is brewing in the Scotch whisky industry over a decision by Diageo to change the composition of its whisky brand Cardhu.

The company has changed the brand from its traditional 12-year-old single malt make-up to a mix of vatted malts. However, it is still selling the Scotch under the same name, changing only part of the labelling to "pure" malt instead of "single" malt.

The decision has prompted great concern and criticism among parts of the drinks community, because of fears it will damage the reputation of the Scotch industry.

Diageo's opponents argue that the new whisky should not be sold as Cardhu, the fifth most popular brand in the world, because it misleads consumers.

A report today in the Scotsman, quoted rival Allied Domecq as denying rumours that it was close to quitting the Scotch Whisky Association over the body's inaction on Diageo's move.

The Scotsman quoted an Allied spokesman saying there was "no truth in the rumour whatsoever".

However the spokesman added that Allied is "extremely concerned about this issue and the reputation of single malt".

In its defence, Diageo says it had been forced to make the change because it is running out of Cardhu.

Peter Smith, Diageo spokesman, told the BBC earlier this week: "We have to respond to consumer demand because in countries such as Spain, Italy, Greece and France, we are seeing a great demand for Cardhu and twelve years ago we never dreamt that would happen.

"We should be celebrating success but we just don't have the stocks, so we are going down this route of introducing - in selected markets - Cardhu which is Cardhu Pure Malt, which is an accepted practice within the industry."