Robert Feather is out to prove the sceptics wrong. A metallurgist with a passion for archaeology, he has been asked to help authenticate what he believes could be one of the most exciting religious discoveries since the Dead Sea Scrolls.

The West London Synagogue member has previously published a book on the Copper Scroll, the Dead Sea Scroll thought to hold clues about the location of buried Temple treasure.Now he is trying to establish the origins of a mysterious cache of metal books which could be linked to the Kabbalah.

The objects belong to Hassan Saeda, a Bedouin farmer in Galilee who says they have been in his family's possession since his great-grandfather found them in a cave in Jordan, a century ago.

His collection consists of more than 20 codices (early books), cast mostly in lead and containing cryptic messages in Hebrew and Greek along with symbols such as the menorah. In various places, the Hebrew letters appear to stand for Bar Kochba, leader of the second-century Judean revolt against the Romans; and the talmudic mystic Shimon bar Yochai, who hid from the Romans in a cave for 13 years.

"The first time I heard about the discovery, I was extremely cautious," Mr Feather said. "However, when I was given an opportunity to see and examine some examples…and visit the cave where they were said to have come from, my scepticism was allayed."

The books appear to be "Kabbalah-related and the nature of the content indicates a magical incantation style of writing," Mr Feather said. Before 400 CE, almost all ancient codices were made of parchment. The lead codices "predate any form of codex by several hundred years and this particular material was probably chosen to ensure permanency."

The Israel Antiquities Authority (IAA), however, has dismissed the idea that the books are of any value. Experts who examined some of them, it said, "absolutely doubted their authenticity". According to the IAA, the books are a "mixture of incompatible periods and styles…without any connection or logic. Such forged motifs can be found in their thousands in the antiquities markets of Jordan and elsewhere in the Middle East."

Professor Andre Lemaire, an expert in ancient inscriptions from the Sorbonne, was also dubious, saying the writing on some of the codices he had seen made no sense and it was "a question apparently of sophisticated fakes".

Undeterred, Mr Feather instead cites the findings of Peter Northover, a metals analyst at Oxford University. Conducting tests on two samples of metal from one book, Dr Northover concluded that their composition was "consistent with a range of ancient lead," and that it was clear from the surface corrosion that the book was "not a recent production".

The IAA remains unconvinced, arguing that the metal could have been taken from an ancient coffin while the messages could have been fabricated later.

But Sasson Bar-Oz, a lawyer representing Mr Saeda, the artefacts' owner, believes that the IAA did not carry out extensive enough checks. "My opinion, after a lot of time on this project," he said, " is that they are genuine."

Now there is fresh hope for Mr Feather, who was approached to help Mr Saeda because of his expertise in metal. A piece of leather, bearing the image of a crocodile, which also turned up with the metal books, was sent for carbon dating. The results, just back, indicate it is nearly 2,000 years old. But Mr Feather said that the dating needed to be corroborated by other tests, currently being conducted, before he could be confident of its accuracy.

The dry soil of the Middle East is rich in the relics of ancient civilisation. But experts do not want to be caught by elaborate forgeries. Last October a marathon five-year trial ended in Israel of two dealers accused of faking an inscription on an ossuary (stone coffin) to suggest that it might have once held the remains of James, the brother of Jesus Christ. The judge has still to announce a verdict and the 12,000 pages of conflicting evidence demonstrate how difficult it can be to determine what is genuine or not.

Institutions involved with antiquities tended to be "ultra-cautious", Mr Feather said, "because they have burned their fingers on previous occasions. A classic example is that of the Shapira strips."

Moses Shapira was a 19th-century antique dealer in Jerusalem who acquired some leather strips which he thought were early biblical writings. "Initially they were hailed as one of the greatest historical finds of all time," he said. "Subsequently the British Museum dismissed them as forgeries, largely because the text differed from the biblical version of the time. Shapira was so distraught that he blew his brains out in a hotel in Amsterdam," he said.

"When the first of the Dead Sea Scrolls was discovered in 1947, similarities to the Shapira texts made scholars reassess their conclusions. It is now generally accepted that the Shapira strips were probably the oldest known version of Deuteronomy."