•Symbols have been spotted in the eyes of the Mona Lisa. Picture: AFP/Getty Images
Leonardo Da Vinci's 500-year-old Renaissance masterpiece has long been steeped in mystery with even today, the true identity of the woman with the alluring smile still far from certain.
The painting also featured in the Dan Brown blockbuster The Da Vinci Code, which was turned into a 2006 film starring Tom Hanks, in which his character interprets secret messages hidden in the Mona Lisa and some of Da Vinci's other paintings, including The Last Supper.
Now members of Italy's National Committee for Cultural Heritage have revealed that by magnifying high resolution images of the Mona Lisa's eyes letters and numbers can be seen.
Yesterday Silvano Vinceti, committee president, said: "To the naked eye the symbols are not visible, but with a magnifying glass they can clearly be seen.
"In the right eye appear to be the letters LV, which could well stand for his name, Leonardo Da Vinci, while in the left eye there are also symbols but they are not as defined.
"It is very difficult to make them out clearly, but they appear to be the letters CE or it could be the letter B. You have to remember the picture is almost 500 years old so it is not as sharp and clear as when first painted.
"In the arch of the bridge in the background, the number 72 can be seen, or it could be an L and the number 2.''
Mr Vinceti, who has travelled to Paris to examine the painting in the Louvre gallery where it is on display, explained that in true Dan Brown style they were put on to the mystery after fellow committee member Luigi Borgia discovered a musty book in an antique shop. The 50-year-old volume describes how the Mona Lisa's eyes are full of various signs and symbols.
He said: "We are only at the start of this investigation and we hope to be able to dig deeper into this mystery and reveal further details as soon as possible.
"It's remarkable that no-one has noticed these symbols before and from the preliminary investigations we have carried out we are confident they are not a mistake and were put there by the artist."
Mr Vinceti, something of a Renaissance "cold case" art historian, is part of the group asking French authorities for permission to exhume Da Vinci's remains from his tomb at Amboise Castle in the Loire Valley.
They want to see if the artist's skull is there so they can try and recreate his face and establish if the Mona Lisa is in fact a self-portrait, as some people believe.
Some historians believe that Da Vinci was homosexual and that his love of riddles led him to paint himself as a woman.Another theory is that the Mona Lisa is in fact Lisa Gheradini, the wife of Florence merchant, and another suggests the subject could be the artist's mother.
Six months ago, Mr Vinceti made headlines around the world after discovering the bones of Renaissance "wild man" artist Michelangelo Merisi, otherwise known as Caravaggio, in a long-forgotten crypt at Porto Ercole on Italy's Tuscan coast.