Billed as a rediscovered masterpiece by Kazimir Malevich, the portrait of a bohemian Russian woman holding a red bag was the charismatic star of a London exhibition in 2014. Critics picked out the image for special praise in the Tate Modern show dedicated to the avant-garde painter.

But now the painstaking research of a Russian art lover has exposed art world chicanery that appears to lead from the Soviet culture wars of the 1930s to the misattribution of a painting since valued at millions of pounds.

Documents gathered by Andrey Vasiliev and shared with the Observer indicate that the portrait of the stage designer Elizaveta Yakovleva and her jaunty red bag is likely to be the work of the woman she once lived with in Leningrad, a former pupil of Malevich called Maria Dzhagubova. She had also designed the fashionably suprematist, or geometric-shaped, bag that Yakovleva holds.

So, though the portrait was praised during the Tate show by Nicholas Cullinan, now director of the National Portrait Gallery, as a work in which Malevich used colour to rebel by “tacitly alluding to the innovations he had pioneered”, it seems it can no longer be regarded as an exciting addition to the figurative output of Malevich, an artist best known for his minimalist 1913 work, Black Square. Cullinan told the Observer he remembers his praise for the work, but had no comment on doubts about its attribution.

Maria Dzhagupova, pictured in the 1910s

The key evidence is a document retrieved from Soviet archives by Vasiliev, a retired psychiatrist, that itemises all the paintings by Dzhagubova that were held by the state. By then socialist realism was the only creative style sanctioned during Stalin’s rule and works by Malevich and his pupils were suppressed.

A Leningrad ledger lists the work as Position 1 – Portrait of Yakovleva estimated at 30 roubles, and gives the inventory number 434 208. This number is still visible on the back of the canvas.

“Fortunately for both posterity and accuracy, some detail-obsessed Soviet bureaucrat scribbled the accession number of the district financial department on the verso of the portrait of an elegant lady with a suprematist bag,” said Vasiliev, adding that Dzhagupova, “a gifted and prodigious artist”, was proud of the portrait. “She included it in the list of her significant creations, supplied for a dictionary of Soviet artists. The portrait was important to her not only because it was one of her better paintings but because Yakovleva was her friend and partner,” he said.

The Tate show, which came to London from the Bundeskunsthalle in Bonn and started in Holland in 2013, displayed the portrait to such advantage that the Stedelijk museum, Amsterdam, was keen to buy it from its Dutch owner, the collector Philip van den Hurk. However, the price asked, of more than €20m, put an end to negotiations.

Trouble started when the portrait was shown in Russia in 2017 at a Malevich exhibition, Not Just the Black Square. Vasiliev had a feeling of déjà vu. The portrait had been offered to him as a work of an unknown artist during the 1980s, he said.

Vasiliev visited a series of St Petersburg archives and the riddle of the lady with a red bag began to unravel. Several documents in the State Archives of Literature and Art were missing. It seemed the name of Dzhagupova was being airbrushed from art history.

State accounts show the painting was sold in 1977 for 14 roubles 40 kopeks and it didn’t reapppear until the end of the 1980s, recorded then as the work of an unknown artist. By the 1990s, when van den Hurk purchased it, Malevich’s signature was there.

Kazimir Malevich. Photograph: Heritage Images/Getty Images

The painting had been authenticated by the time it was seen in the west and was later certified by Andrei Nakov, a French art historian, who expressed doubts about the artist’s signature. He said: “I developed certain doubts about the portrait, especially after I saw the X-ray of it. I believe that it was started by Malevich but finished by another artist. In future when I publish a new addition of the catalogue raisonné I will address this issue.”

Without seeing the original, the leading American expert on Malevich, Charlotte Douglas, took it to be an authentic Malevich in her essay on his use of textiles in an edition of Art Journal from 1995.

Any attempt to reach Yakovleva, the sitter for the portrait, to settle the issue would by then have been in vain . She had died in the siege of Leningrad in 1942 and the last person close to her, Dzhagubova herself, had died alone in 1975, leaving no family.

For Vasiliev the story of the portrait is illuminating. “On the one hand, art experts and museum curators elevated the painting created by the unknown pupil of Malevich to the level of masterpiece,” apparently without being able to check its provenance, he said. “On the other - the tale of the female artist whose name was erased to appropriate her work as a creation of the great ‘dead white man’ of the Russian avant-garde fits perfectly into contemporary feminist discourse.”

Yet Vasiliev also suspects Dzhagupova might have been pleased about the misattribution. “As the devoted pupil of Malevich, who idolised her teacher, she might have been proud that her painting was taken for the best work of his later period.”