Criminal gangs in Italy have found a lucrative new way of earning money - hijacking lorries containing wheels of Parmesan cheese.

Police say there have been a spate of cheese raids. Gangs lie in wait at service stations on the Milan-Bologna motorway to ambush drivers when they stop for coffee. In one instance, a driver was threatened by four armed men, tied up and gagged, and his van carrying 300 wheels of cheese was driven away. The wheels were taken to an industrial estate, cut up and then sold in stores.

According to Giorgio Ciroldi of Ferrarini in Reggio Emilia, one of the biggest producers of the sharp and granular cheese, the stolen Parmesan usually ends up in the south of Italy, on sale in corner shops where no questions are asked about its provenance.

'Like other commercial items, such as computers or clothes, the gangs who steal cheese may have connections with organised criminal networks such as the Mafia or the Camorra,' said a Carabinieri spokesman. 'It is common for these gangs to arrive in northern Italy by train or aeroplane and to take part in these kinds of crimes with local accomplices.'

To counter the thefts, producers and the Italian farmers' union, Coldiretti, are experimenting with microchips hidden in the crusts of the cheese, which means they are more easily identifiable. Markings burnt on to the crust can also help police track the stolen cheese.

Although similar hard cheese is made all around the world, the authentic Parmesan comes from a specific area around Parma and Reggio Emilia and is made from cows' milk. It is stored for up to two years in carefully controlled conditions before being sold and has been given the EU's protected geographical indication status.

The average Italian family is said to eat half a kilo of Parmesan a week, mostly by sprinkling it on pasta. A recent survey by Coldiretti also found that Parmesan is the most shoplifted item in Italy, accounting for 10 per cent of goods stolen from shops.