For more than a year, this village has been a focus of weekly protests against the Israeli security barrier, which cuts through its lands. Now, the village appears to be at the center of an intensifying Israeli arrest campaign.

Apparently concerned that the protests could spread, the Israeli Army and security forces have recently begun clamping down, arresting scores of local organizers and activists here and conducting nighttime raids on the homes of others.

Muhammad Amira, a schoolteacher and a member of Nilin’s popular committee, the group that organizes the protests, said his home was raided by the army in the early hours of Jan. 10. The soldiers checked his identity papers, poked around the house and looked in on his sleeping children, Mr. Amira said.

He added, “They came to say, ‘We know who you are.’ ”

Each Friday for the last five years, Palestinians have demonstrated against the barrier, bolstered by Israeli sympathizers and foreign volunteers who document the ensuing clashes with video cameras, often posting the most dramatic footage on YouTube.

Israel says the barrier, under construction since 2002, is essential to prevent suicide bombers from reaching its cities; the Palestinians oppose it on grounds that much of it runs through the territory of the West Bank.

While the weekly protests are billed as nonviolent resistance, they usually end in violent confrontations between the Israeli security forces and masked, stone-throwing Palestinian youths. “These are not sit-ins with people singing ‘We Shall Overcome,’ ” said Maj. Peter Lerner, a spokesman for the Israeli Army’s Central Command, which controls the West Bank. “These are violent, illegal, dangerous riots.”

Other Palestinians are “jumping on the bandwagon,” he said, and the protests “could slip out of control.”

The protests first took hold in the nearby village of Bilin, which became a symbol of Palestinian defiance after winning a ruling in the Israeli Supreme Court stipulating that the barrier must be rerouted to take in less agricultural land. According to military officials, work to move the barrier will start next month.

Like a creeping, part-time intifada, the Friday protests have been gaining ground. Nabi Saleh, another village near Ramallah, has become the newest focus of clashes, after Jewish settlers took over a natural spring on village land.

One recent Friday, a group of older villagers marched toward the spring. They were met with tear gas and stun grenades, and scuffled with soldiers on the road. Other villagers spilled down the hillsides swinging slingshots and pelted the Israelis with stones.

“Israel recognizes the threat of the popular movement and its potential for expanding,” said Jonathan Pollak, an Israeli anarchist and spokesman of the Popular Struggle Coordination Committee, which is based in Ramallah. “I think the goal is to quash it before it gets out of hand.”

In recent months the Palestinian Authority president, Mahmoud Abbas, and other leaders of the mainstream Fatah Party have adopted Bilin as a model of legitimate resistance.

The movement has also begun to attract international support. The Popular Struggle Coordination Committee receives financing from a Spanish governmental agency, according to the committee’s coordinator, Mohammed Khatib of Bilin.

“Bilin is no longer about the struggle for Bilin,” said Mr. Khatib, who was arrested in August and has been awaiting trial on an incitement charge. “This is part of a national struggle,” he said, adding that ending the Israeli occupation was the ultimate goal. Before dawn on Thursday soldiers came to Mr. Khatib’s home in Bilin and took him away again.

Israel security officials vehemently deny that they are acting to suppress civil disobedience, saying that security is their only concern. Among other things, they argue that the popular committees encourage demonstrators to sabotage the barrier, which Israel sees as a vital security tool.

The Israeli authorities have also turned their attention to the foreign activists, deporting those who have overstayed visas or violated their terms. In one case soldiers conducted a raid in the center of Ramallah, where the Palestinian Authority has its headquarters, to remove a Czech woman who had been working for the International Solidarity Movement, a pro-Palestinian group.

Israeli human rights groups like B’Tselem and Yesh Din have long complained of harsh measures used to quell the protests, including rubber bullets and .22-caliber live ammunition. The Israeli authorities say the live fire is meant to be used only in dangerous situations, and not for crowd control. But the human rights groups say that weapons are sometimes misused, apparently with impunity, with members of the security forces rarely held to account.

About a hundred soldiers and border police officers have been wounded in the clashes since 2008, according to the military. But the protesters are unarmed, their advocates argue, while the Israelis sometimes respond with potentially lethal force.

Tristan Anderson, 38, an American activist from Oakland, Calif., was severely wounded when he was struck in the forehead by a high-velocity tear-gas canister during a confrontation in Nilin last March.

After months in an Israeli hospital, Mr. Anderson has regained some movement on one side, and has started to talk. But he has serious brain damage, according to his mother, Nancy, and the prognosis is unclear.

The Andersons’ Israeli lawyer, Michael Sfard, is convinced that the tear-gas projectile was fired directly at the protesters, contrary to regulations. Yet the Israeli authorities who investigated the episode recently decided to close the case without filing charges.

The investigation found that the Israeli security forces had acted in line with regulations, according to Israeli officials. But witnesses insist the projectile was fired from a rise only about 60 yards from where Mr. Anderson stood. If it had been fired properly, in an arc, they contend, it would have flown hundreds of yards. Nineteen Palestinians have been killed in confrontations over the barrier since 2004. A month after Mr. Anderson was wounded, Bassem Abu Rahmah, a well-known Bilin activist, was killed when a similar type of tear-gas projectile struck him in the chest.

Aqel Srur, of Nilin, one of three Palestinians who gave testimony to the Israeli police in the Anderson case, was killed by a .22-caliber bullet in June.

So far, the activists seem undeterred. Salah Muhammad Khawajeh, a Nilin popular committee member and another local witness in the Anderson case, related that when he was summoned for questioning two months ago, he was warned that he could end up like Mr. Srur.

Mr. Khawajeh’s son, 9, was wounded in the back of the head by a rubber bullet at a protest this month.

But as Mr. Khawajeh put it, “We still come.”