Olivier Picasso, grandson of the great Pablo Picasso, is to raffle one of his grandfather's masterpieces for charity on December 18 in Paris.

With the event overseen by Sotheby's, 50,000 tickets will be made available at a cost of $135 each. This is the first time any of Picasso's works have been sold in this way.

The piece is entitled L'homme au gibus, or The Man with the Opera Hat, and is estimated to be worth around $1m. Proceeds from the sale will benefit preservation projects in the Lebanese city of Tyre, which was badly damaged during the Lebanese civil war and is now a UNESCO World Heritage site.

"My grandfather was a pioneer, he was happy to be the first in every kind of situation," Olivier Picasso told Sky News.

"He was a helpful person, very generous, giving money around him during many difficult times."