A bottle of the world's most expensive whisky is going on auction in Edinburgh and could sell for up to £900,000.

Described as the "Holy Grail" of whisky, the 60-year-old Macallan Valerio Adami 1926 is going under the hammer on October 3.

Bonhams say the exceptional rarity and quality of the whisky bottle mean it is estimated to sell for between £700,000 and £900,000.

Just 12 of the bottles, which feature a label designed by pop artist Alerio Adami, were ever produced.

Another bottle of The Macallan Alerio Adami 1926 was sold at Bonhams Hong Kong for a record-breaking price of £814,081 in May this year.

It was the highest price ever paid for a bottle of whisky at a public auction.

Experts do not know exactly how many of the original 12 bottles still exist.

One may have been destroyed in an earthquake in Japan, while at least one has been opened and consumed.

Bonhams whisky specialist Martin Green said: "The Macallan 1926 60-year-old has been described as the Holy Grail of whisky.

"Its exceptional rarity and quality puts it in a league of its own, and the world's most serious whisky collectors will wait patiently for many years for a bottle to come onto the market.

"It is a great honour to be offering this amazingly rare whisky at our Edinburgh sale."

International whisky consultant Charles MacLean said: "Macallan single malt is the darling of whisky collectors and The Macallan Adami 1926 - with its Peter Blake stablemate - sits at the very pinnacle of the distillery's distinguished output.

"All the appeal of Scotch whisky - the myth, the tradition and the romance - find its ultimate expression in this bottle."