The Shroud of Turin was made by medieval artist Giotto, it was claimed yesterday.
The 14ft length of fabric, said to be the burial cloth of Christ, bears a faint image of a man and appears to be stained by blood.
However carbon-dating tests have suggested it was produced between 1260 and 1390.
Now Italian art expert Luciano Buso has suggested that the original cloth deteriorated and Giotto was asked to make a copy.
After months of careful examination of photographs of the Shroud - the relic is kept locked away and not available to be viewed unless on special occasions - Luciano Buso has come up with an idea worthy of a Da Vinci Code thriller.
He says that several veiled appearances of the number 15, hidden in the fabric by the artist, indicate Giotto created the Shroud in 1315 - and that it is a copy of the original which had been damaged and was then lost over the centuries.
Giotto was perhaps the best known artist of his time and was made famous for his decoration of the Scrovegni Chapel in Padua, the fresco that depicts the life of the Virgin Mary and Christ.
Mr Buso insists that 700 years ago it was common practice for artists to insert partial dates into their works so as to guarantee their authenticity and it was known only to a handful of people so as to avoid forgeries.
His claims, which form part of a new book he has written, would coincide with 1980's carbon dating - which has been dismissed by the Church - and which puts the Shroud's origins in the early 14th century.
e wasn't trying to fake anything, which is clear from the fact that he signed it ''Giotto 15'', to authenticate it as his own work from 1315. This was not a fake he was asked to make a copy of the original one.
No-one at Turin Cathedral where the Shroud is kept was available for comment but Professor Bruno Barberis, director of the Shroud Museum, said: 'I think the theory is ridiculous.
'His claim that Giotto made the Shroud are not very convincing to me and as far as we are concerned it was not made by an artistic method. Many people claim to have seen Greek and Hebrew writing in the Shroud but it's never been proven.
'We believe that the image on the Shroud was made by the body of a man who was tortured and then crucified - however there are still many tests that need to be carried out to prove one way or another what it's origins are.'
Last year Pope Benedict spent several minutes kneeling in front of the linen cloth, after it went on display for only the fifth time in 100 years and he was one of two million people who saw it during a six week viewing.
The Shroud has captivated the imagination of historians, church elders, sceptics and Catholics for more than 500 years.
Nazi dictator Adolf Hitler was obsessed by it and wanted to steal it so he could use it in a black magic ceremony, a monk revealed for the first time last year.
The 14ft-long Shroud bears the faint image of the front and back of a tall, long-haired, bearded man and appears to be stained by blood from wounds in his feet, wrists and side.
Originally the Vatican had intended for the Shroud's next display to be 2025 but in 2009 Pope Benedict announced it would be brought forward 15 years.
For centuries debate has raged whether the image is that of Christ or an expert forgery from the Middle Ages but what is certain is that experts have never really been able to explain how the image was made.
Carbon-dating tests were conducted on the cloth in 1988 and suggested it was from between 1260 and 1390, other scientists have since claimed that contamination over the ages, from water damage and fire, were not taken sufficiently into account and could have distorted the results.
As a result of controversy and the fact that dating techniques have improved significantly since the 1988 tests were done, there have been numerous calls for further testing but the Vatican has always refused.
The Shroud was given to the Turin archbishop in 1578 by the Duke of Savoy and has been kept in the Cathedral ever since.