It contains six bound sheets of 24 carat gold, with illustrations of a horse-rider, a mermaid, a harp and soldiers.

The book dates back to 600BC

It has now been donated to the museum by its finder, on condition of anonymity.

Reports say the unidentified donor is now 87 years old and lives in Macedonia.

The authenticity of the book has been confirmed by two experts in Sofia and London, museum director Bojidar Dimitrov said quoted by AFP.

The six sheets are believed to be the oldest comprehensive work involving multiple pages, said Elka Penkova, who heads the museum's archaeological department.

There are around 30 similar pages known in the world, Ms Penkova said, "but they are not linked together in a book".

The Etruscans - one of Europe's most mysterious ancient peoples - are believed to have migrated from Lydia, in modern western Turkey, settling in northern and central Italy nearly 3,000 years ago.

They were wiped out by the conquering Romans in the fourth century BC, leaving few written records.