Tests on a 2,000-year-old stone box support claims that it once held the bones of James, said to have been the brother of Jesus and an important early Christian leader, scientists have concluded.
The results of the experiments, which are disclosed in a television documentary, back the suggestion that the "bone box", or ossuary, may be the oldest archaeological link with Christ.
Last year, the tomb ossuary, inscribed with the words "James, son of Joseph, brother of Jesus", came to light in Israel, prompting speculation over whether it was genuine or a fake and whether it referred to Jesus of Nazareth.
Since then, the box has been subjected to tests which are consistent with it coming from the right place and the right time, said Dr Ed Keall, a curator at the Royal Ontario Museum. "It is a genuine box with a genuine inscription, dating from first century AD, likely from the Silouan Valley, Jerusalem," he said.
He argued that it was rare for the inscription to refer to a brother - they usually mentioned the father - although he agreed that this fell short of proof that it contained the bones of James.
The findings will revive interest in James, whose major role in early Christianity has been eclipsed by St Peter and St Paul. He is described in two of the Gospels as the brother of Jesus, but in some traditions he is thought of as merely a cousin.
Scholars believe that he became the leader of the early Christian movement in Jerusalem following Jesus's crucifixion, but he may have regarded himself as a member of a sect of Judaism rather than of a new religion. Fr Jerome Murphy-O'Connor, the uncle of the Archbishop of Westminster and leading Biblical authority, said: "James was a Jew who became a follower of Jesus and remained true to his Jewish faith.
"He was the leader of the Mother Church, the Church of Jerusalem, during its adolescent years, its whole formative period."
The limestone burial box measures 20in by 22in by 10in and carries a worn pattern of six pointed stars on one side. On the other is an inscription with distinctive letters: "Ya'akov, bar Yosef, akhui di Yeshua" - "James [Ya'akov], son of Joseph [Yosef], brother of Jesus [Yeshua]." The words are in Aramaic, the language spoken by Christ, and close to ancient Hebrew.
The palaeographers date the style of lettering to around 50 AD. This timing is just right for a memorial to James who, according to the "Jewish Antiquities" of Josephus, was stoned to death for his beliefs in AD 62.
In the journal Biblical Archaeology Review, Prof Andre Lemaire of the Sorbonne, Paris, concluded that it could be the earliest artefact relating to Jesus. Now scientists have backed his contention with tests.
A team at the Geological Survey of Israel extracted the patina, a cream-coloured film adhering to the stone, and found it matched that inside one of the letters after a study with electron microscopy, as would be expected with the genuine item.
The Royal Ontario Museum in Toronto subjected the inscription to a tougher test, using long-wave ultraviolet light which should highlight attempts to fake it. Again, it looked genuine, said Dr Keall.
Prof Camil Fuchs, of Tel Aviv University, analysed the probability that the James ossuary refers to the Jesus of the New Testament, after critics said James, Jesus and Joseph were common names in first century Palestine.
He concluded that the inscription on the ossuary probably referred to James, son of Joseph, brother of Jesus of Nazareth. "Also, I have to point out that out of the thousands of ossuaries that have been found, there is only one - other than the James ossuary - that mentions not just the deceased, and his father, but the brother," said Prof Fuchs.
Because the ossuary did not come from a controlled excavation, where archaeologists plot every detail and possible clue to a discovery's context, scholars said they despaired of ever knowing the inscription's meaning beyond doubt.
Another issue is how many times the ossuary has been used. There is no way to tell that the bone fragments it contains are of St James or of a later lodger.
The present owner, Oded Golan of Tel Aviv, bought the box from a Jerusalem antiques dealer in the 1970s. Mr Golan said he never suspected the ossuary could be linked to Christ.