Dominic Currie, 58, said he opened a suitcase at his home in Fife and found what could have been a long-lost masterpiece, along with various items of Russian origin.
Edinburgh-based art expert Bendor Grosvenor found the Russian memorabilia had been bought over the past six months on the online auction site eBay.
An item bought on 1 April appeared to be a frame similar to one holding a photograph of the man Mr Currie claimed was his father, Nicolai Vladimirovich.
Mr Grosvenor pointed out that the Russian name consists of a Christian name and a patronymic, and does not contain a surname.
Mr Currie, a pop artist from Methil, had said the “Picasso” painting, which bears a close resemblance to a genuine Picasso painting entitled Portrait of Khanweiler, was due to be examined by Christie’s auctioneers in London tomorrow.
He has now admitted the painting is a fake, claiming it is an “experiment” and “performance art”.
“I don’t do hoaxes but it was an experiment,” he said.
“It was a piece of performance art in order to raise awareness of the struggling artists in Scotland.
“I’m trying to be as honest as possible. I did a piece of performance art, it’s got a lot of media attention because any kind of celebrity gets a lot of attention.
“What doesn’t get the attention is the struggling artist in Scotland.
“I think the public will understand when you report the fact that it was done as a piece of performance art in order to highlight the plight of ordinary artists who never get a break, who end up with a degree, selling shoes and pizzas because they never get a break.”
He added: “As a pop artist that borrows explicitly from other artists’ work I was interested in exploring aspects of authenticity in the modern media world.
“Thus the story of the Picasso discovery was merely an experiment and a piece of performance art as a way towards putting this to the test.”
Mr Currie is believed to have been renowned for recreating classic paintings when he attended Adam Smith College in Glenrothes.
A former classmate, who did not wish to be named, said: “In college he was known for being able to forge several famous painters’ work. For one of our exhibitions he recreated a Jack Vetriano painting, the one of the couple ballroom dancing on a beach, but with the twist of it being Methil beach in Fife.”
Mr Currie would not confirm or deny claims made about copying other artists’ work.
Previously, he claimed the painting had belonged to his mother who revealed only two years before she died in 2000 that, during 1955, she had fallen pregnant to a Russian soldier.
According to the artist, she also revealed her Soviet lover had gifted her a painting to sell but he dismissed her story as fantasy until he opened the suitcase himself four weeks ago.