It has lived through the Ottoman Empire, the British mandate and the creation of the State of Israel. But the days of a 1,500-year-old olive tree in Israel's West Bank could be numbered.

A British tree consultant is leading a campaign to save the 1,500 year old tree in the West Bank village of Al Walaja, close to Bethlehem.

It grows close to Israel's proposed route of the West Bank security barrier.

Southampton-based tree consultant Jeremy Barrell has been asked by local resident and olive farmer Abu Waji, who lives close by, to assess the value of the tree.

Mr Barrell has invented a special system to judge whether a tree is worth saving. He said the West Bank tree was the highest scoring tree he had ever evaluated: "There are three heritage characteristics that always crop up; visibility, scientific importance and cultural value. The maximum possible score for any tree is 20 heritage points, and this tree has hit that maximum; it is not possible to find a more important heritage tree."

Mr Barrell said that the construction of the barrier's foundations and buffer zone would cause such significant damage to the tree that it was unlikely to survive.

He claimed he was not interested in "local politics" but simply cared about protecting trees. "We aren't activists. I don't mind which side of the wall the tree ends up on, as long as it isn't destroyed. It's just a tree issue, at the end of the day."

"Ancient trees are just like old people, they are particularly vulnerable to changes around them, and for trees, even the smallest disruption in their rooting environment can tip them into an irreversible spiral of decline."

A spokesman for the Israeli embassy said that every effort would be made to make sure the tree was not harmed by the construction, and that there were many experts in Israel who would assess what would cause the tree the least damage, even if it meant moving it.