Ancient symbols on a 3,200-year-old stone slab have been deciphered by researchers who say they could solve "one of the greatest puzzles of Mediterranean archaeology".

The 29-metre limestone frieze, found in 1878, in what is now modern Turkey, bears the longest known hieroglyphic inscription from the Bronze Age. Only a handful of scholars worldwide, can read its ancient Luwian language.

The first translation has offered an explanation for the collapse of the Bronze Age's powerful and advanced civilizations.

The script tells how a united fleet of kingdoms from western Asia Minor raided coastal cities on the eastern Mediterranean.

It suggests they were part of a marauding seafaring confederation, which historians believe played a part in the collapse of those nascent Bronze Age civilisations.

Researchers believe the inscriptions were commissioned in 1190 BC by Kupanta-Kurunta, the king of a late Bronze Age state known as Mira.

The text suggests the kingdom and other Anatolian states invaded ancient Egypt and other regions of the east Mediterranean before and during the fall of the Bronze Age.

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Archaeologists have long attributed the sudden, uncontrollable collapse of the dominant civilisations around 1200BC partly to the impact of naval raids. But the identity and origin of the invaders which modern-day scholars call the Trojan Sea People, had puzzled archaeologists for centuries.

The new findings follow research by an interdisciplinary team of Swiss and Dutch archaeologists.

They include Dr Fred Woudhuizen, thought to be one only 20 people in the world who can read Luwian. He translated the inscription.

The 35cm-tall, 10-metre-long limestone slab was found 1878 in the village of Beyköy, 34 kilometres north of Afyonkarahisar in modern Turkey. French archaeologist George Perrot copied the inscription before the stone was used by villagers as building material for the foundation of a mosque.

The copy was rediscovered in the estate of English prehistorian James Mellaart after his death in 2012 and was handed over by his son to Dr Eberhard Zangger, president of the Luwian Studies foundation, to study.

Mr Zangger, a Dutch linguist and expert in Luwian language and script, said the inscription suggested "Luwians from western Asia Minor contributed decisively to the so-called Sea Peoples’ invasions - and thus to the end of the Bronze Age in the eastern Mediterranean".

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The foundations said: "One of the greatest puzzles of Mediterranean archeology can thus be plausibly solved."