The olive harvest was off to a bad start for Said Abu Aliya -- branches torn from the Palestinian farmer's trees lay scattered on the ground, along with bright-green olives.

He blamed Israeli settlers in a nearby hilltop camp, and Israeli soldiers patrolled as a buffer while he and his family picked the remaining crop.

''Without their presence, we wouldn't be able to enter our lands because the settlers would attack us,'' said the 47-year-old.

For many Palestinians, the fall harvest of some 10 million trees used to be a joyful ritual steeped in tradition. But the West Bank's olive groves have increasingly become a target of extremist Jewish settlers who, hilltop by hilltop, seek to expand their control over land they say they were promised by God.

Just in the first two weeks of this season, farmers say, assailants beat a 63-year-old olive picker, slashed another man's car tires, tried to chase Palestinians out of several groves and stole or damaged some of the crop. In one incident captured on video, four settlers punched and kicked a Palestinian photographer and a foreign activist in an olive grove.

Compounding the farmers' problems, more trees are harder to reach because they lie beyond Israel's lengthening West Bank separation barrier or close to Jewish settlements and their multiplying satellite camps.

Israeli human rights activists say securing the harvest is an important test of Israel's obligation as an occupying power to protect Palestinians. They say the military and police are doing a better job than in the past, but have failed to protect crops or bring vigilantes to justice.

This week Palestinian President Mahmoud Abbas complained that the army isn't doing its job, raising questions about whether Israel is serious about peace with Palestinians. Israeli Defense Minister Ehud Barak denounced those attacking farmers as ''hooligans,'' but said troops are making a major effort to protect farmers. The military said soldiers have been briefed about the importance of the harvest, jeeps patrol trouble areas and officers are given maps to rule on ownership disputes.

In the past, Israeli troops have destroyed thousands of Palestinian olive trees along roadsides to protect against snipers and stone throwers. Palestinians still complain that settlers are often given free rein by the military. For example, the settlers who were filmed attacking the photographer were allowed to walk away, while police arrested three Israelis helping with the harvest for entering a ''closed military area.''

A settler leader, Yitzhak Shadmi, dismissed reports of vandalism as staged.

Growing numbers of Israelis and foreigners are flocking to the groves to help the farmers. Yaakov Manor's Harvest Coalition helped arrange West Bank trips for hundreds of Israelis last year.

Thousands of Palestinians take part in the harvest, with students given time off to help and professionals returning to their villages. Olive oil is a food staple, and even the leftovers from the oil presses are used as fuel.

The economic benefits are relatively modest -- about $100 million from an expected 21,000 tons of olive oil this year -- but the extra income reaches some 100,000 families. For some, it's just pocket money, for others enough to plan a wedding or build a house.

Near the village of Burin, Amneh Abdel Qader sat on a tarpaulin under a tree, as her son, daughter-in-law and three grandsons combed the branches with handheld rakes. The olives tumbled onto the tarp, and the 70-year-old sorted them, the plumpest for eating and the rest for oil.

''We used to bring a radio and have fun, sing and enjoy ourselves,'' Abdel Qader said. ''But from the day they came,'' she said, referring to Israeli settlements near her village, ''we can't relax anymore.''

Burin's farmers can only reach lands near the settlements of Yitzhar and Bracha with special coordination from security forces. Farmers say they're allowed to visit those areas only twice a year, for planting and harvesting, and that they need more access to hang traps for olive flies, prune branches and clear underbrush.

Israel's Civil Administration, the branch of the military dealing with the Palestinians' day-to-day life, denied any quota on visits, but a senior official said the idea is to keep settlers and farmers away from each other.

''You can smell the fuel in the air,'' the official said on condition of anonymity, in line with briefing regulations. ''We don't want to have a situation where the olive harvest is setting off the atmosphere again.''

At times, there's also lack of coordination within the military.

In the village of Naalin this month, near Israel's separation barrier, border police fired tear gas and stun grenades as villagers and volunteers tried to reach a grove. The army had given a permit for the Naalin harvest but apparently not briefed the border police, said Rabbi Arik Ascherman of Rabbis for Human Rights. Several Israelis were injured and three detained, he said.

The Palestinian olive harvest falls about 5 to 10 percent short of its potential every year because of settler violence and Israeli restrictions, estimated Palestinian economist Samir Hleileh. Israel requires permits for villagers who have land in the roughly 10 percent of the West Bank swallowed up on the ''Israeli'' side of the barrier.

Eighty percent of the people who used to work these lands no longer get permits, according to U.N. monitors.

Mohammed Jabareen, mayor of the village of Taibeh, which has 250 dunams (60 acres) of land beyond the barrier, said landowners have received permits, but not all of the workers needed for the harvest. The army says it's issuing extra permits during the harvest.

Some are trying to improve output by teaching farmers how to grow premium oils for export. Industrialist Bassem Khoury has invested in a premium oil storage facility with 30 steel vats, even though business prospects are uncertain.

''To me,'' he said, ''the olive tree is a symbol of Palestine.''