An inscription on a clay slab unearthed at the birthplace of the ancient Olympic Games in Greece could be the oldest written excerpt from Homer's epic poem the Odyssey ever discovered, officials said.

The Greek culture ministry said an initial estimate dates the slab, inscribed with 13 verses from the Odyssey's Book 14, to the Roman period, possibly before the third century.

If this estimate is confirmed, the slab could be a "magnificent archaeological, epigraphical, literary and historic item", the ministry said.

The artefact was found near the Olympia sanctuary during digs carried out under the direction of Ilia Antiquities Ephorate director Kolia Erofili-Irida in co-operation with a team of archaeologists from German universities.

The Games were held at Olympia in southern Greece from 776BC to 393AD.

Homer's Odyssey is one of the fundamentals of the western literary canon, first thought to have appeared in the eighth century BC.

It tells the story of the Greek hero Odysseus' 10-year journey home from the Trojan wars, and his battles against monsters, witches and other foes as he seeks to reunite with his wife Penelope and son Telemachus on Ithaca.