and Jackie McGlone It is one of the most iconic paintings to hang in any UK gallery, one of the best known images of Christ, and Salvador Dali's most famous work.

But now a friend of the Spanish artist claims Glasgow's Christ of St John of the Cross, voted Scotland's favourite painting, was not painted solely by Dali.

Stan Lauryssens, a Belgian crime writer whose own colourful life story is now being made into a film starring Al Pacino and Cillian Murphy, was once jailed for selling bogus Dali paintings, an occupation that made him millions of pounds.

In an interview with The Herald, Lauryssens says he believes the famous figure of Christ in the Glasgow-owned painting was in fact painted by one of his assistants. He claims Dali did not have the artistic skill to paint the image of the body of Christ.

Lauryssens has written about his experiences in Dali and I: Exposing the Dark Circus of the International Art Market, the basis for the movie in which Pacino will play Dali.

When the writer was on the run from authorities in Belgium, he moved to Spain and became a friend of the painter. He became part of the inner circle of Dali's associates, including his assistants, led by a painter named Isidro Bea. Eventually Lauryssens was caught and jailed in Spain, where he served four months for selling the fake paintings.

Lauryssens says that only the lower section of the Glasgow painting, the seascape area with figures depicted beneath the hanging figure of Christ, was painted by the Spanish master of surrealism.

"Dali could not have painted the figure of Christ on the cross - he categorically could not paint musculature like a Renaissance artist," he said.

"Instead, he paid someone to hang on a cross and photographed him from above; then his assistants, like Isidro Bea, worked from that image.

"This is still a genuine Dali, though, because it is a work of genius - and it was his vision, his imagination, his creativity that made it."

Glasgow bought the painting from Dali in a now famous deal in 1951, brokered by Dr Tom Honeyman, the director of Glasgow Museums. Its cost of £8200 was considered high but, crucially for the city, also included the copyright.

The image is now so famous and popular that the city has recently hired lawyers to search the world for breach of copyright in an attempt to recoup lost revenue and start legal action against those who refuse to comply.

Last night, Mark O'Neill, head of museums for Culture and Sport Glasgow, dismissed Lauryssens' claim.

"It is just speculation. It is strange, because one of the serious criticisms of Dali is that he was too facile, too skilled, that he could draw anything and was therefore too slick," he said.

"This is not based on evidence, but based on speculation about Dali's abilities. Artists have used assistants throughout history, but usually it is the other way around to what Mr Lauryssens is suggesting - the artist will paint the main figure and the assistants fill out the rest of the painting. It's rarely claimed the assistants are more skilled than the main artist."

He added: "I would like to see evidence that he lacked technical proficiency. I don't think this holds any water. Dali was in some ways a disturbed and disreputable character and I can see why a crime writer would be interested in him, however."

Julian Spalding, the former director of art galleries and museums in Glasgow, Sheffield, Manchester, and and now a writer on art, added: "I think this is nonsense. Dali could paint anything, there should be no doubt over his ability to reproduce anything, there's nothing he could not do.

"He had tremendous technical ability, and the sheer quality of the painting of the Christ figure is fantastic. The concept was Dali's and the execution was Dali's, which is not to say he did not get some help from assistants. I think his reasoning on this is all wrong: Dali loved painting muscles and bulges and hair and all those things."

A spokesman for Culture and Sport Glasgow, which runs the city's museums and art galleries, released a statement that read: "Mr Lauryssens is entitled to his opinions. However, Mr Lauryssens is not an artist, not an art expert and his dealings in the sale of art have led him through an extremely chequered past."

The Herald Magazine