A Roman fresco recovered by art police from a private house in Paris last month went on show to the public for the first time in Rome on Thursday.

Archaeologists believe the painting was illegally removed during the 1970s from the walls of a villa in Oplontis, one of the towns covered in ash and cinder during the eruption of Vesuvius in AD 79.

Dating to the first century AD, the painting shows a bower of vines, a satyr riding a mule, and a cloaked woman making a sacrifice at an altar.

The three-metre long fresco is the largest landscape-themed painting ever found in the Vesuvian area. ''It's rare to see a landscape fresco of these dimensions,'' said government archaeology chief Stefano De Caro.

''Usually they are small pictures showing ports or wild nature scenes. But here we have a rural landscape, with rows of vines and a big shrine - perhaps that of Dionysus (the Greek god of wine),'' he added.

Although archaeologists have yet to work out exactly where the fragmented fresco comes from, De Caro said it may once have decorated exterior walls overlooking a garden.

Italian art police worked with Swiss, Belgian and French investigators to track down the painting, which they knew had been in Geneva in the early 1980s. The fresco hung for some time in the house of a rich industrialist in Brussels before eventually finding its way to Paris.

Investigators discovered the painting in the house of French publisher and art collector Jacques Marcoux in Place Vendome in February.

After its 40-year trip abroad, the fresco has gone on display at Palazzo Massimo as part of an exhibition of wall paintings from Pompeii, Herculaneum and other Vesuvian towns that runs until March 30.

De Caro said the fresco would be returned to the Pompeii archaeology superintendency when the show ends.