A previously unknown sketch by Leonardo Da Vinci has been valued at $15.8m.

The remarkable piece, which has been confirmed as genuine by experts at New York's Metropolitan Museum of Art, was discovered by the Tajan auction house in Paris.

The auction house claims this is the first new work by Da Vinci to be uncovered in 15 years

It was one of 14 drawings brought in to be valued by an elderly doctor.

The work is a study of Saint Sebastian and is believed to date to between 1482 and 1485, when Da Vinci was living and working in Milan.

It shows a bound figure against a backdrop of mountains and appears to have been drawn in preparation for a larger work.  

It's thought to be one of eight figures of Saint Sebastian listed in Da Vinci's Codex Atlanticus, which features much of his original drawing and writing.  

While the figure shows all the hallmarks of the artist's style, the reverse also offers clues. It displays notes and diagrams in Da Vinci's hand on light and shadow.

The auction house states this is the first new piece by Da Vinci to be uncovered in the past 15 years. It will be sold sometime next year.

Da Vinci's work is rarely offered and always attracts strong competition.

Most recently his Salvator Mundi made a record $127.5m in a private sale in 2013.

That could be exceeded soon by Lady with an Ermine (1490), which the Polish government intends to secure for the nation. It carries a value of around $240m. It's said to be the only Da Vinci painting left in private hands.