The image on the left is a digital reconstruction of what Mr Cotte claims to have found underneath the Mona Lisa
An image of a portrait underneath the Mona Lisa has been found beneath the existing painting using reflective light technology, according to a French scientist.
Pascal Cotte said he has spent more than 10 years using the technology to analyse the painting.
He claims the earlier portrait lies hidden underneath the surface of Leonardo's most celebrated artwork.
A reconstruction shows another image of a sitter looking off to the side.
The Louvre Museum has declined to comment on his claims because it "was not part of the scientific team".
Instead of the famous, direct gaze of the painting which hangs in the Louvre Museum in Paris, the image of the sitter also shows no trace of her enigmatic smile, which has intrigued art lovers for more than 500 years.
But Mr Cotte's claims are controversial and have divided opinion among Leonardo experts.
Will Gompertz, Arts Editor
I'm sceptical. It's perfectly common for an artist to overpaint an image as it is for a client who's commissioned that artist to ask for changes. So it's not surprising that there are those underpaintings on the Mona Lisa.
The data that the technology generates is open to interpretation, which needs to be analysed and corroborated by the academic and curatorial community, and not just an individual. I think the Louvre's decision not to make a comment is telling.
This is the world's most famous painting which, like a celebrity, always makes for a good story. But in this case I think caution is required.
The scientist, who is the co-founder of Lumiere Technology in Paris, was given access to the painting in 2004 by the Louvre.
He has pioneered a technique called Layer Amplification Method (LAM), which he used to analyse the Mona Lisa.