Art experts believe a new portrait by Leonardo da Vinci may have been discovered thanks to a 500-year-old fingerprint.

A Young Girl in Profile in Renaissance Dress, the painting which has been attributed to Leonardo da Vinci. Photograph: Christie's

The small picture of a young woman in profile was previously believed to be a German work from the early 19th century and has changed hands in recent years for around £12,000.

But a growing number of leading Leonardo scholars agree the work is almost certainly by the Renaissance figurehead because it appears to have his fingerprint on it. Carbon dating and infrared analysis of Leonardo's techniques back up the theory.

If the scholars are correct, it will be the first major work by Leonardo to be identified for 100 years and will be worth tens of millions of pounds.

Martin Kemp, emeritus professor of the history of art at Oxford University, is so convinced the portrait is a Leonardo that he has written an as yet unpublished 200-page book about it.

Kemp said he first thought the find was "too good to be true – after 40 years in the Leonardo business I thought I'd seen it all".

But gradually, "all the bits fell into place like a well-made piece of furniture. All the drawers slotted in," he told the Times.

The fingerprint, which corresponds to the tip of the index or middle finger, was found by Peter Paul Biro, a Montreal-based forensic art expert, when he examined images taken of the portrait by the revolutionary multispectral camera. Multi-spectral analysis can capture light from frequencies beyond the visible light range, such as infrared, allowing the extraction of information that the human eye fails to capture.

Biro believed the fingerprint, which was found near the top left corner of the work, was "highly comparable" to a fingerprint on Leonardo's St Jerome in the Vatican, the Antiques Trade Gazette reported.

The magazine said infrared analysis showed "significant" stylistic parallels with those in Leonardo's Portrait of a Woman in Profile in Windsor Castle and showed the work was made by a left-handed artist, as Leonardo is known to have been.

Drawn in ink and chalks, the beautiful young woman's costume and elaborate hairstyle reflected Milanese fashion of the late 15th century, and carbon analysis was consistent with that dating, the magazine reported.

Kemp believed that "by a process of elimination", the fresh-faced teenager could be Bianca Sforza, the daughter of Ludovico Sforza, Duke of Milan from 1452-1508, and his mistress Bernardina de Corradis.

Kemp said he thought the portrait, which measures 33cm x 22cm (13in x 9in), must date from around 1496 when, aged 13 or 14, the Bella Principessa married the Duke's army captain, Galeazzo Sanseverino, a patron of Leonardo's. She died four months after the wedding.

It would be Leonardo's first known portrait of the princess, although he painted two of the duke's mistresses Cecilia Gallerani and Lucrezia Crivelli.

The picture was sold at Christie's in New York in 1998, in an Old Master Drawings sale as a Young Girl in Profile in Renaissance Dress, catalogued as German, early 19th century, with an estimate of $12,000-$16,000.

It sold for $19,000 (£12,000) and later went for a similar sum to Canadian-born collector Peter Silverman, in 2007.

Silverman believed there was more to the portrait and delved into the matter after a discussion last year with Dr Nicholas Turner, formerly the keeper of prints and drawings at the British Museum.

Silverman told the Times that when he first saw the picture, "my heart started to beat a million times a minute. I immediately thought this could be a Florentine artist. The idea of Leonardo came to me in a flash."

The portrait is due to go on display in an exhibition in Sweden next year.