Professor Yona Sabar is one of the last Jews on the planet who could have a conversation with Jesus, in his mother tongue.

When Professor Sabar arrived in Israel from northern Iraq in 1951, he imagined the language he grew up speaking was Kurdish - until a Hebrew University academic identified it as Aramaic.

Now an LA-based academic who has devoted his life to the study of the language, Professor Sabar believes he is now one of the last speakers of the language, and has embarked on a project to find other speakers of Aramaic, which has more than 100 dialects, before the language is lost forever.

The professor and his son Ariel spoke last week at the Royal Geographical Society in London about his experiences growing up in Zakho, Iraqi Kurdistan, documented in his son's book, My Father's Paradise.

Kurdish, Aramaic-speaking Jews are believed to have been the world's oldest Jewish diaspora, and have possibly the most compelling claim to be one of the "lost tribes".

Ariel Sabar has compared biblical descriptions of towns and rivers to the places where his father grew up. Jews were exiled in the eighth century BCE to Assyria, now Kurdish Iraq. The biblical Habor river is believed to be the modern-day Habur river. "My father swam in that river," said Mr Sabar. "But no one knew Jews were still there. They are written off in the Bible as 'lost'.

"They were in the mountains, not accessible to Western scholars. No one knew they were there. So they got on and lived their own life, until the founding of the state of Israel. That flushed them out of the mountains. They had been missing for nearly 3,000 years, but they were not lost. They'd just gone off the radar."

Yona Sabar was the last boy to be barmitzvah in Zakho. Although they had lived in harmony with their Muslim neighbours, life changed very quickly after 1947. He now recalls that "the situation in Iraq was getting worse and worse. We were identified as an extension of the state of Israel, and they transferred that hatred of Zionists to us. Nobody wants to get up and leave a place where you were born, where you have a business, but people saw they had to abandon the sentimentality they had about the place.

"The whole community left together, only very few stayed. We lived there as a group, you can't stay without a kosher butcher, without a synagogue, without a minyan. When I went back there for the first time in 1992, one person said to me that they were descendents of Jews, whose grandparents had converted to Islam."

Once in Israel as a teenager, Yona Sabar became terrified of losing the ability to speak his own language, even before he knew its significance, writing words down on scraps of paper.

Now, he said: "It's difficult to know how many people are left who still speak Aramaic. The older generation who spoke it in their childhood have often stopped speaking it, forgotten it, they have grown up speaking a different language. Very few are speaking it every day."

His son said he speaks just "three or four words" of Aramaic. "And if anyone should know it, it should be me right? But I don't. The importance of what my father is doing is not about keeping it alive; it's not realistic. The idea is to record as many of this last generation as possible."

Since moving to the US to study, Professor Sabar has contributed lines of Aramaic to many Hollywood films and shows, including George Burns' Oh God!, The X-Files and Curb Your Enthusiasm, although not The Passion of the Christ:

"Mel Gibson wanted a Christian to do it," Professor Sabar revealed.