Unmasked, the famous brothers whose disguise duped art world

Avant-Garde artists Konstantin and Yuri Shamanov were billed as the stars of the show, a new exhibition of contemporary Russian works at Orel Art, a smart Westminster gallery.

The founders and leaders of Moscow's radical underground Chameleon art movement, announced the gallery, would "take the viewer on a journey from the past to a present reality to uncover a diseased contemporary existence".

At last week's opening of the Good News! exhibition, London's art world was suitably impressed by their paintings, collages and sculptures. But some puzzled at the origins of the Shamanov brothers and a movement they had never encountered before.

Today, the Evening Standard can reveal they are an elaborate hoax. In fact, they are the Chapman brothers, leading lights of London's contemporary art scene, rather than Moscow's.

A simple internet search, which showed no trace of their work before the exhibition, reinforced this news-paper's suspicions.

"But the news could not be contained after our successful opening last week - critics, collectors, curators and public alike started asking who these artists they had never heard of were, what is the Chameleon movement?

"The exhibition catalogue presents a very funny biography on the artists, giving away slightly the fictional nature of this project." The Chapman brothers declined to comment, but a source close to their studio said: "I can't definitely confirm that it is them, but all the evidence suggests it might be.

"They have certainly been taking a great deal of interest in all things Russian lately."

The "Shamanov" art included works such as Konstantin's collage Hang this Rebel and Yuri's etchings with titles like Constructivist Bee and Study for a Flower Satellite. The exhibition's publicity material also included photographs of the normally close-cropped Chapmans disguised with beards and long hair.

In an interview they were reluctant to discuss their work - "it is like asking a sand dune to explain concrete" - but happy to expand on Konstantin's army service with a youthful Roman Abramovich: "He drank petrol. When he smoked, he set his hair on fire."

Some critics saw the stunt as a comment on the influence of Russian money on the art world. The gallery, which specialises in Russian art, said all their other artists are "100 per cent Russian". The exhibition runs until 1 October.

Last year the Chapmans bought a series of Adolf Hitler watercolours for £115,000, which they adorned with rainbows, stars and hearts and put back on the market for £685,000.

In 2003, they defaced a series of Goya's etchings by adding funny faces.

Sham lives of the shamanovs

Yuri and Konstantin Shamanov are well known in Russian underground art circles as the founders and leaders of a new art movement called Chameleon. Working out of Moscow, this movement challenges the mores of a "diseased present" ...

It was only in the late Nineties that they finally reunited and started working as artists. Their work is inspired by the Russian avant-garde movements such as constructivism or Malevich's suprematism and loaded with references to the past. The constructivist-inspired piece at Orel Art UK is their first joint work.