The last portrait by renowned Austrian artist Gustav Klimt before his death is expected to sell for up to £65 million at auction later this month.

Dame Mit Facher (Lady With A Fan), described as a “technical tour de force”, will be offered in Sotheby’s marquee modern and contemporary evening auction in London on June 27.

The painting was created when Klimt was in his artistic prime, and at a moment when the “formality” of his earlier commissioned work gave way to a new expressivity.

The artist died unexpectedly in 1918 at the age of 55.

Klimt started work on Lady With A Fan in 1917, by which time he was among the most celebrated portraitists in Europe, receiving commissions at prices far higher than his contemporaries.

However, this was a rare work painted entirely in the pursuit of his own interests and demonstrates a “freedom and spontaneity” that reflects Klimt’s joy in painting, experts said.

Unlike traditional vertical “portrait” paintings, Lady With A Fan returns to the square format that Klimt used for his avant-garde landscapes earlier in the century, giving this painting a uniquely “modern” edge.

The painter’s fascination with Chinese and Japanese art and culture also shines through in the depiction of the silken kimono worn by the subject.

Helena Newman, chairman of Sotheby’s Europe and worldwide head of impressionist and modern art, said the painting was “full of boundary-pushing experimentation”.

“Dame Mit Facher (Lady With A Fan) is the last portrait Gustav Klimt created before his untimely death, when still in his artistic prime and producing some of his most accomplished and experimental works,” she said.

“Many of those works, certainly the portraits for which he is best known, were commissions.

“This, though, is something completely different – a technical tour de force, full of boundary-pushing experimentation, as well as a heartfelt ode to absolute beauty.”

The painting was acquired shortly after Klimt’s death by Viennese industrialist Erwin Boohler, whose family was close friends and patrons of both Klimt and fellow painter Egon Schiele.

The exhibition at Sotheby’s New Bond Street galleries later this month will see three major portraits by the artist on view simultaneously in the capital for the first time.

Lady With A Fan will be displayed alongside Hermine Gallia, of 1904, and Adele Bloch Bauer II, of 1912, which are currently on view in the National Gallery’s After Impressionism show.

Sotheby’s Modern and Contemporary evening auction on June 27 will also include a strong grouping of portraits by leading artists such as Alberto Giacometti, Edvard Munch, Leonor Fini, Elizabeth Peyton and Kerry James Marshall.