Rare Whisky 101 co-founder David Robertson collecting a sample from a bottle of Macallan 1878 whiskey for testing, which has turned out to be a worthless fake. PRESS ASSOCIATION Photo.

An exclusive whisky costing almost £7,600 a dram (€8,500) has turned out to be a worthless fake.

The bottle was thought to be the world's only known Macallan 1878 still in circulation but has been exposed as an impostor made in the 1970s.

Experts made the discovery after a customer at The Waldhaus Hotel Am See in St Moritz paid 9,999 Swiss francs (around £7,565) for a nip.

David Robertson, co-founder of Rare Whisky 101, said: "The Waldhaus team have done exactly the right thing by trying to authenticate this whisky.

"Over the past year, we have been invited by numerous bottle owners and auction houses to assess suspicious bottles.

"Indeed, we've noticed an increasing number of old, rare archive or antique bottles coming to market at auction, and it's difficult to know how prevalent this problem is.

"We would implore that others in the market do what they can to identify any rogue bottles.

"The more intelligence we can provide, the greater the chance we have to defeat the fakers and fraudsters who seek to dupe the unsuspecting rare whisky consumer."

The price paid by the customer suggested it could be the world's most expensive dram, causing a stir among whisky experts who began to question its authenticity.

The investigation found it to be a modern fake, most likely a blended scotch made up of 60% malt and 40% grain.

Had the bottle been genuine, it would have carried a bar value of around 300,000 Swiss francs (£227,000).

But having been proved to date back no further than 1970, the team claim the spirit is "worthless" as a collector's item.

Hotel manager Sandro Bernasconi has flown to Asia in the last week to refund the paying customer in full.

Online Editors