A team of historians says the lost city of the Incas, Machu Picchu, in Peru was discovered more than 40 years earlier than previously thought and ransacked.

The story about its discovery by the western world has been shaken up by a team of historians who say a German businessman looted its treasures more than 40 years before.

They say the adventurer, Augusto Berns, who traded in Peru's wood and gold, raided the citadel's tombs in 1867 apparently with the blessing of the Peruvian government.

He had set up a sawmill at the foot of the forested mountain on which Machu Picchu stands and systematically robbed precious artefacts which he sold to European galleries and museums.

Only when one of the historians found a map in Peru's national museum were his activities traced.