SCIENTISTS and art experts have found a hidden painting beneath one of Pablo Picasso's first masterpieces, The Blue Room, using advances in infrared imagery to reveal a bow-tied man with his face resting on his hand.

Now the question conservators at The Phillips Collection in Washington hope to answer is simply: Who is he?

It is a mystery that is fuelling new research about the 1901 painting created early in Picasso's career while he was working in Paris at the start of his distinctive blue period.

Over the past five years, experts have developed a clearer image of the mystery picture under the surface which is a portrait of an unknown man painted in a vertical composition.

Patricia Favero, a conservator at The Phillips Collection who pieced together the infrared image of the man's face, said: "It's really one of those moments that really makes what you do special."