A Vatican researcher rekindled the age-old debate over the Shroud of Turin, saying that faint writing on the linen proves it was the burial cloth of Jesus.

Experts said the historian may be reading too much into the markings, and they stand by carbon-dating that points to the shroud being a medieval forgery.

Barbara Frale, a researcher at the Vatican archives, said in a new book that she used computer-enhanced images of the shroud to decipher faintly written words in Greek, Latin and Aramaic scattered across the cloth.

She asserts that the words include the name "(J)esu(s) Nazarene" - or Jesus of Nazareth - in Greek.

That, she said, proves the text could not be of medieval origin because no Christian at the time, even a forger, would have mentioned Jesus without referring to his divinity. Failing to do so would risk being branded a heretic.

"Even someone intent on forging a relic would have had all the reasons to place the signs of divinity on this object," Ms Frale said. "Had we found 'Christ' or the 'Son of God' we could have considered it a hoax, or a devotional inscription."

The shroud bears the figure of a crucified man, complete with blood seeping from his hands and feet, and believers say Christ's image was recorded on the linen's fibres at the time of his resurrection.

The fragile artefact, owned by the Vatican, is kept locked in a protective chamber in a Turin cathedral and is rarely shown. Measuring 13 feet long and three feet wide, the shroud has suffered severe damage through the centuries, including from fire.

The Roman Catholic Church makes no claims about the cloth's authenticity, but said it is a powerful symbol of Christ's suffering.

There has been strong debate about it in the scientific community.

Sceptics point out that radiocarbon dating conducted on the cloth in 1988 determined it was made in the 13th or 14th century.

But Raymond Rogers of Los Alamos National Laboratory said in 2005 that the tested threads came from patches used to repair the shroud after a fire.

Mr Rogers, who died shortly after publishing his findings, calculated it is 1,300 to 3,000 years old and could easily date from Jesus' era.

Another study, by the Hebrew University, concluded that pollen and plant images on the shroud showed it originated in the area around Jerusalem sometime before the eighth century.

While faint letters scattered around the face on the shroud were seen decades ago, serious researchers dismissed them, due to the results of the radiocarbon dating test, Ms Frale said.

But when she cut out the words from enhanced photos of the shroud and showed them to experts, they concurred the writing style was typical of the Middle East in the first century - Jesus' time.

She believes the text was written on a document by a clerk and glued to the shroud over the face so the body could be identified by relatives and buried properly. Metals in the ink used at the time may have allowed the writing to transfer to the linen, Ms Frale said.

She said she counted at least 11 words in her study of enhanced images produced by French scientists in a 1994 study. The words are fragmented and scattered on and around the image's head, crisscrossing the cloth vertically and horizontally.

One short sequence of Aramaic letters has not been fully translated. Another fragment in Greek - "iber" - may refer to Emperor Tiberius, who reigned at the time of Jesus' crucifixion, Ms Frale said.

She said the text also partially confirms the Gospels' account of Jesus' final moments. A fragment in Greek that can be read as "removed at the ninth hour" may refer to Christ's time of death reported in the holy texts, she said.

In her book The Shroud of Jesus Nazarene, published in Italian, Ms Frale reconstructs from the lettering on the shroud what she believes Jesus' death certificate said: "Jesus Nazarene. Found (guilty of inciting the people to revolt). Put to death in the year 16 of Tiberius. Taken down at the ninth hour."

She said the text then stipulates the body will returned to relatives after a year. Ms Frale said her research was done without the support of the Vatican.

"I tried to be objective and leave religious issues aside," Ms Frale said. "What I studied was an ancient document that certifies the execution of a man, in a specific time and place."