It is perhaps Italy's best-known export, but a number of Italy's best-known olive oil producers are being investigated for fraud.
Italy's anti-fraud police squad in Turin is examining whether seven well-known olive oil brands – Carapelli, Bertolli, Santa Sabina, Coricelli, Sasso, Primadonna and Antica Badia – have been selling lesser-quality virgin olive oil as "extra virgin" olive oil.
According to allegations in Italian press reports, samples taken from those brands found that they did not meet EU labelling rules for extra virgin olive oil. The EU has quality criteria that extra-virgin oil has to meet, such as its degree of acidity.
On its website, Pietro Coricelli rejected the allegations, arguing the test was flawed and unreliable. It said its oil had been carefully analyzed by both its own analysts and outside laboratories.
CNBC was unable to contact Deolio, a Spanish company which owns Bertolli, Carapelli and Sasso, for comment. Eurospin, an Italian supermarket which sells the Antica Badia range, declined to comment. The Italian newspaper La Repubblica reported that the companies involved all denied the allegations, however.
Supermarket Lidl, which sells the Primadonna brand, told CNBC in a statement that the allegations do not affect British consumers.
"Lidl is aware of this issue and is taking it very seriously. The background to this is an Italian test report on flaws found in extra virgin olive oil in Italy. The supplier for the 'extra virgin olive oil' products depicted in the test report does not, however, deliver product to Lidl U.K. Since Lidl U.K. sources its olive oil from other suppliers, it was not affected by these test results."
Extra virgin is the best quality olive oil as it comes from the first press of olives. Virgin olive oil is of a lesser quality but is above plain olive oil. Extra virgin olive oil can cost between 30 – 40 percent more than its lower quality cousin, according to Italian magazine, Il Test, which first discovered the alleged fraud.