The famous fresco is already the focus of mythical speculation after author Dan Brown based his "The Da Vinci Code" book around the painting, arguing in the novel that Jesus married his follower, Mary Magdelene, and fathered a child.

Now Slavisa Pesci, an information technologist and amateur scholar, says superimposing the "Last Supper" with its mirror-image throws up another picture containing a figure who looks like a Templar knight and another holding a small baby.

"I came across it by accident, from some of the details you can infer that we are not talking about chance but about a precise calculation," Pesci told journalists when he unveiled the theory earlier this week.

Websites www.leonardodavinci.tv, www.codicedavinci.tv, www.cenacolo.biz and www.leonardo2007.com had 15 million hits on Thursday morning alone, organisers said, adding they were trying to provide a more powerful server for the sites.

In the superimposed version, a figure on Christ's left appears to be cradling a baby in its arms, Pesci said, but he made no suggestion this could be Christ's child.

Judas, whose imminent betrayal of Christ is the force breaking the right-hand line of the original fresco, appears in an empty space on the left in the reverse image version. And Pesci also suggests that the superimposed version shows a goblet before Christ and illustrates when Christ blessed bread and wine at a supper with his disciples for the first Eucharist.

The original Da Vinci depicts Christ when he predicts that one among them will betray him.