Judas, the disciple blamed for betraying Jesus Christ to the Romans, was a hero, a newly released ancient text says.

National Geographic revealed Thursday what it calls the Gospel of Judas, a 1,700-year-old text which reverses the accepted view of the religious villain.

"Jesus Christ asks Judas to betray him to the authorities," National Geographic said in a story about the 26-page text posted on its website.

The 1,700-year-old script is written in Coptic, an ancient Egyptian language. (Associated Press)

In the Bible's New Testament Gospels, Judas betrayed Jesus for 30 pieces of silver, and then stricken by remorse, returned the bribe and committed suicide.

But the codex, or ancient book, says Jesus asked Judas to betray him.

In the text, Jesus tells Judas: "'You will exceed all of them. For you will sacrifice the man that clothes me.'"

In that passage, "Jesus says it is necessary for someone to free him finally from his human body, and he prefers that this liberation be done by a friend rather than by an enemy," said Rodolphe Kasser, a clergyman, a former professor at the University of Geneva in Switzerland and head of the translation team.

"So he asks Judas, who is his friend, to sell him out, to betray him. It's treason to the general public, but between Jesus and Judas, it's not treachery."

The text is expected to be controversial because it contradicts nearly 2,000 years of Christian thought.

National Geographic said in the early days of Christianity there were competing doctrines, and the codex probably reflects the thinking of the Gnostics, a group that hid its writings when they were denounced by the established church.

The manuscript was mentioned around AD 180 by Bishop Irenaeus of Lyon, who called it fictitious.

"Let a vigorous debate on the significance of this fascinating ancient text begin," Rev. Donald Senior, president of the Catholic Theological Union of Chicago, told the Associated Press.

Appears real

The text, written in Coptic script, is believed to be a translation of an original Greek text written by Christians before AD 180.

It was found in Egypt in the 1970s, and an antique dealer tried to sell it several times, including to Yale University. But Yale declined, doubting its provenance.

The codex was finally transferred to the Maecenas Foundation for Ancient Art, based in Basel, Switzerland, which worked with the National Geographic Society and the Waitt Institute for Historical Discovery in California to restore, translate and publish the book.

The University of Arizona carbon-dated five tiny samples of papyrus and leather binding to between AD 220 and AD 340, and other tests backed up that conclusion.

Pages were put on display at the National Geographic Society's headquarters in Washington, which has also published Coptic and English versions of the text. The codex will later be sent to Egypt.