A potent symbol of peace and harmony, the olive has become a source of confrontation and violence in the decades-old conflict that pits Israel against Palestinians.

Once a time of happy industry, the autumn harvest season in particular has degenerated into antagonism, with Palestinian farmers accusing extremist Jewish settlers of destroying their crops and trying to seize their land.

Nawaf Thawabteh said he had barely started picking his oil-rich fruit in early October on a rocky hilltop near the Elon Moreh settlement when three masked men brandishing clubs charged through his orchard and grabbed his half-filled sacks.

"The army was meant to be here to protect us, but there was no one around. It is just getting worse and worse," said Thawabteh, sitting beneath one of his trees, with the West Bank city of Nablus shimmering in the distance.

An estimated 10 million olive trees dot the Israeli-occupied West Bank, thriving in the arid climate and covering 45 percent of all agricultural land in the region.

But settler attacks are taking their toll, says the United Nations, which has recorded a surge in general violence this year. Vandals have not only snatched harvested olives, but also destroyed thousands of trees.

The U.N. body for Palestinian humanitarian affairs, OCHA, says 7,500 trees were uprooted, burnt or chopped down in the first nine months of 2011. Palestinian authorities say 800,000 trees have been destroyed since the 1967 war, when Israel seized the small, kidney-shaped territory.

The Israeli army, which controls security in most of the West Bank, says it takes farmer protection seriously and plans for the harvest as though it were a military operation.

One of the top commanders in the territory agrees that settler violence poses a real problem, but says it is tough to eradicate what he believes to be random acts of criminality.

"It is very hard to catch the vandals. We have 10 million trees here and can't defend all 10 million. It is not our only problem," said the commander, who declined to be named.

"Ninety nine percent of settlers maintain law and order. ... Unfortunately one percent, or maybe less, support these people," he added, speaking from his West Bank headquarters.

SETTLEMENT KILLINGS

Palestinians question the army's commitment to defending their farmers, pointing to the fact that few vandals are ever caught. The Israeli NGO Yesh Din says that of 127 cases of tree destruction it has followed since 2005, only one ended in court.

Some 350,000 Israeli settlers live in the territory, which they call Judea and Samaria, claiming a biblical birthright to land that Palestinians want for their own, independent state.

Peace talks aimed at ending the conflict broke down last year following a dispute over Jewish settlement building and repeated attempts to revive the negotiations have failed. In the meantime, the construction work continues.

OCHA says there are some 135 settlements. They are deemed illegal by the World Court, something Israel disputes, and often abut agricultural land farmed by Palestinians for generations.

Fearing attacks from Palestinians, the communities are ringed with security fences and the army has set up wide buffer zones, giving farmers a limited timeframe to enter the fields and take care of the crops under their supervision.

Even within those set periods, violence can flare.

When Nizam Qawarek, 37, was told by commanders that he could go and collect olives near the Itamar settlement, close to Nablus, he immediately rushed to his silvery green trees.

He and his wife had barely begun work before they were confronted by dozens of angry residents from Itamar. "They were waving Israeli flags and shouting there shouldn't be any Arabs here. They threw stones at us. It was terrifying,," he said.

Itamar residents justified their actions, saying they didn't want Palestinians near their property following the murder in March of five members of one family, including two children and a baby, who were stabbed to death in their house.

Two local Palestinian youths have admitted to the killings.

"Only six months after the murder, while our blood is still boiling and the residents are still caring for their bleeding wounds, allowing anyone from the Awarta village, where the murderers ... came from, is outrageous and negligent," Itamar rabbi, Avichai Rozenki, said in a statement.

The settlers say the killers used last year's harvest to spy on Itamar from up close and find a way to break in.

Settler leaders say talk of widespread destruction is wildly exaggerated.

"The announcements that are going out almost daily about damage caused to Arab land and olive groves is totally incredible. If true, it would be visible, everywhere. But it is not," said settler spokesman David Ha'ivri.

"Most of people here, Jews and non-Jews, are interested in living out their lives and raising their families peacefully," added Ha'ivri, who has been in the West Bank for over 20 years.

COUNTING THE COST

British charity Oxfam estimates that olive output accounts for 15-19 percent of agricultural production in the territory, generating revenues of $160-190 million and guaranteeing livelihoods for the families of some 100,000 farmers.

The farmers maintain that the aggression is all part of a concerted effort to sweep them from the sun-soaked land.

Maazoza Zaben says settlers torched 270 of her trees in Borin in September, leaving an ugly black smear across the hill.

"They want us to leave the land. It will be easier to chase us away if we don't have our trees. But even if they kill me, I won't leave this place," said the 58-year-old widow.

Farmers who have land near settlements and the West Bank security barrier say they have to count the cost not just of trashed trees, but also of restrictions on access rights.

Outside the harvesting season, the army says it does not have the resources to oversee the pruning and ploughing that is vital to keep the groves healthy and prevent thick thorn bushes from taking root between the gnarled, squat trees.

The day he was chased from his land, Qawarek also lost 30 trees near the Itamar settlement fence in an unexplained blaze.

Having been prevented from ploughing, Qawarek stood helplessly by as the flames leapt from tree to tree, roaring along the parched thorns like electricity surging through wires.

The army says limited manpower also means it cannot provide security to everyone at the height of the autumn harvest. As a result, it opens the season early and offers villagers far less time than they would like to collect the green and black olives.

"The trees would be perfect in two or three weeks time," said Mohamed Shamih, 47, who had been given the all-clear to go to his trees near Elon Moreh in early October.

"I will get 50 percent less oil by harvesting now, but that is better than losing the lot," he added.

Local children take time off school and much of the village turns out to help pluck the olives from the trees, some of which date back 2,000 years to the Roman era, but even the mass mobilisation won't be enough to bring home all the fruit.

"I will have to return to my own land like a thief to try and get the rest," Shamih said, sitting atop his tractor.