The artefacts date from the 8th century BC to the 5th century AD

The ring was allegedly headed by an 82-year-old Austrian guide, whose home in Linz has been described as a "museum" by a senior police official.

The artefacts include ceramics but also pieces of gold and silver, including a cup worth several thousand euros.

The Austrian, nicknamed "Mozart", has not been arrested because of his age.

Five Italians, believed to be tomb raiders and collectors, have been arrested on charges related to international art trafficking and 28 more are under investigation.

The Austrian is said to have gained access to protected archaeological sites thanks to his tour guide credentials.

"His house was just like a museum, with objects on display and ready to be sold," police Col Ferdinando Musella said at a news conference in Rome.

'Only shards'

Some 600 artefacts are said to have been illegally excavated at Crustumerium, an Etruscan city on the outskirts of the capital which was later conquered by the Romans.

But other objects recovered came from Sicily and Puglia in southern Italy.

The Austrian, whose identity was not revealed by Italian investigators, was later quoted by local media as saying that, rather than cultural assets, the objects were simply "shards".

He added he had bought them at fairs in Italy over a period of 40 years.

"If I had stolen the exhibits I wouldn't have been so stupid as to show them publicly and give lectures - even with video clips - on my work in Italy," he said.

The Italian authorities hope the artefacts, which are exceptionally well-preserved, will finally go on display at Italian museums.