Whisky fans, look away now - the world is facing a shortage of a single malt Scotch.

According to a CNN report, distilleries simply can't keep up with demand.

"The shortage of old and rare single malt ... has already started, and it's going to get worse," Rickesh Kishnani, who launched the world's first whisky investment fund, said.

Global single malt sales rose by 159 per cent between 2004 and 2014, according to the Scotch Whisky Association.

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Many new markets have a growing thirst for the drink - particularly Asia, which now consumes one-fifth of all Scotch exports.

Because single malt whisky takes years to produce - by law, all Scotch whisky must be aged for at least three years - and the best are aged much longer - distilleries have been unable to quickly ramp up production.

About 20 million casks are currently maturing in warehouses in Scotland.

Experts say the shortage could last 10-15 years and push up prices considerably.

The Investment Grade Scotch Whisky Index, which tracks the value of high-end whiskies, increased by 14 per cent last year.

"We are currently working at full capacity - seven days a week, 24 hours a day," said Charlie Whitfield, a brand manager for Scotch whisky firm Macallan.

Macallan is currently building a 100 million ($210 million) second distillery which is expected to open in 2017.

American distillers making bourbon whisky are facing similar problems.