A previously unknown Hans Memling panel that was discovered in a private collection earlier this year is to provide one of the main draws of New York's Old Masters Week, when it is offered by Sotheby's on January 31.

The piece, entitled Christ Blessing, will be sold with a $1m-1.5m estimate during the Important Old Master Paintings and Sculpture auction. It has been consigned from a private New England collection, with the auction seeing the work appear in public for the first time in more than 150 years.

Sotheby's and the world's leading experts on the Flemish master have teamed up to confirm the piece as a genuine Memling. It is believed to have been created between 1480 and 1485, and is a superb example of the artist's work as a leading painter of the Northern Renaissance.

The current owners of the piece are said to have been unaware of its value and importance, and it was extremely dirty when first discovered. Sotheby's experts used cutting-edge technology in their research of the panel, which has shed new light on Memling's processes and has since been endorsed by leading figures from Musea Brugge in Belgium and New York's Metropolitan Museum of Art among others.

Also starring during Sotheby's Old Masters Week auctions will be a recently discovered William Blake illustration, which could see $600,000. Sign up to Paul Fraser Collectibles' free weekly newsletter for more of the latest from across the art world.