The decision by Diageo to alter the contents of its Scotch brand Cardhu is continuing to cause controversy.

Diageo, because of what it says are a shortage of stocks, has changed Cardhu from a single malt into a vatted malt. However, opponents of the move claim consumers are being mislead because the packaging for the brand has remained almost unchanged.

The independent Scottish family-owned distiller William Grant & Sons has once more lodged its opposition to the move. In a statement released to today it welcomed the news that Diageo had publicly agreed not to turn any of its other brands marketed as single malt into vatted malts.

However its said it is urging Diageo to reconsider its decision to turn Cardhu into a vatted malt.

"This move, which has caused outrage across the Scotch whisky industry, is unprecedented and will seriously undermine the integrity and authenticity of the single malt category," it said in a statement released yesterday.

Deputy group managing director of William Grant & Sons Ltd Tony Hunt: "By adopting a policy for short term financial gain, Diageo may cause irrevocable long-term damage to the single malt category as consumers around the world begin to question the integrity and provenance of other single malts.

"Other malt whisky companies have sometimes failed to forecast demand 12 years ahead. These companies have taken the long-term view, and either removed their age statement or rationed the stocks available for sale for a while."

"Diageo is the first company who have simply decided to bottle a mixture of other malt whiskies using the existing brand name of a Single Malt Whisky. Once Diageo has done this, any other distiller short of stock could follow suit. It has taken fifty years to build the Single Malt category to its current value, and it is incredible to think that this value could be thrown away by Diageo," he said.

In the statement, William Grant said that despite some claims to the contrary, Cardhu Pure Malt, a vatting of any number of single malt whiskies from various Diageo sources, is now available in the UK, and has also been spotted in France, Hungary, Austria, Greece and Spain, Cardhu's biggest market.

The momentum behind the 'stop Cardhu' campaign is gathering pace in official circles as well. Alex Salmond, former leader of the SNP said at the weekend: "It is probably the most foolish thing I have seen in the whisky industry for 30 years. It seems to be sacrificing long-term consumer confidence for short-term profit."

Meanwhile, a Scottish Labour MP put forward a parliamentary motion calling for a halt to the current methods being used to market Cardhu "pure malt".

Mark Lazarowicz, MP for Edinburgh North and Leith, said yesterday that his motion in the House of Commons had already gained support from a handful of English and Scottish MPs, including both Labour and Liberal Democrats.