A previously unknown self-portrait of Vincent Van Gogh has been discovered hidden behind another of the artist’s paintings.

The self-portrait was found on the back of Van Gogh’s Head of a Peasant Woman when experts at the National Galleries of Scotland took an X-ray of the canvas ahead of an upcoming exhibition.

The work is believed to have been hidden for more than 100 years, covered by layers of glue and cardboard when it was framed in the early 20th century.

Van Gogh, who posthumously became one of Western art’s leading figures, died in poverty and was known for turning canvases around and painting on the other side to save money.

The portrait shows a bearded sitter in a brimmed hat.

Experts said the subject was instantly recognisable as the artist himself, and is thought to be from his early work.

The left ear of the sitter is clearly visible. Van Gogh famously cut his off in 1888.

Frances Fowle, a senior curator at the National Galleries of Scotland, described the discovery as “thrilling”.

“Moments like this are incredibly rare,” she said.

“We have discovered an unknown work by Vincent Van Gogh, one of the most important and popular artists in the world.”

The gallery said experts are evaluating how to remove the glue and cardboard without harming Head of a Peasant Woman.

Visitors to an upcoming Impressionist exhibit at the Royal Scottish Academy in Edinburgh, which runs from late July until the end of November, can see an X-ray image of the self-portrait through a lightbox.