Police in Rome have sniffed out a cannabis factory in an abandoned metro tunnel built during the rule of Fascist leader Benito Mussolini, in the 1930s.

Officers reportedly stumbled across the factory after smelling the pungent crop near an entrance, not far from the Italian central bank.

The tunnel, just over half a mile (1km) long, was also being used to cultivate mushrooms.

But behind a makeshift wall, police discovered rows of marijuana plants.