Israeli soldiers and police on Wednesday detained Brad Lander, the Democratic nominee for a New York House seat, along with about 80 American and Israeli rabbis and activists who were helping Palestinian farmers pick olives in the occupied West Bank.

The group was working a family grove in Nahalin, a village outside Bethlehem near the Israeli settlement of Beitar Illit. After roughly two hours, drones circled overhead and forces arrived, declared a closed military zone and took the volunteers to a police station for questioning, NPR reported from the scene. Two Israeli lawyers who handle such cases told NPR it was the largest mass detention of activists in the West Bank in at least a decade. Rabbi Arik Ascherman, a longtime Israeli human rights campaigner, called it “unprecedented.”

Mr. Lander was let go with a warning, Al Jazeera reported. “I’ve been released from IDF custody with a ‘warning,’ apparently because of my public profile (I told them I wasn’t even a congressmember yet, just a nominee),” he wrote on X, according to MS NOW. “But several dozen rabbis & participants harvesting olives with me are still in detention. For harvesting olives. They should all be released immediately.”

A woodcut-style illustration shows a basket of olives beneath a large olive tree, with soldiers escorting civilians through a rocky, terraced olive grove.

They were held for hours longer. By Wednesday afternoon, all but four had been freed, Beck Strober, a spokesperson for the Protect the Harvest coalition, told NBC News. Mr. Lander later said everyone in the delegation was out. The Israelis in the group are barred from the West Bank for 28 days, the spokesperson said, which Mr. Lander said would keep them from the rest of the harvest.

The Israeli military said in a statement that it detained a “number of” Palestinian harvesters and “dozens of people” with them because no one had filed an advance request with the authorities before the season began. “Coordinating the harvest is required in order to ensure the maintenance of security in the area and public order,” it said. On Mr. Lander, it told NPR: “Regarding reports of the detention of a congressional candidate, we note that he was released once the matter was brought to our attention.”

A woodcut-style illustration shows an olive branch crossing a locked iron gate, with terraced olive groves stretching across hills beyond.

Mr. Lander rejected the military’s account. “We were on private Palestinian land. We were with the farmers whose land it is. There’s no obligation to coordinate with the Israeli military,” he told NPR and WBUR’s Here & Now. He said no one asked the group to leave, and that if they had, “we would have left.” Maps that the Israeli Defense Ministry’s Civil Administration gave Palestinian farmers showed the grove lay outside the areas that need advance coordination, amNY reported.

Israel’s Foreign Ministry called the episode a “stunt” in a social media post. It said Mr. Lander’s team had contacted Israeli representatives in the United States before the trip and was told coordination was required. “Brad Lander came looking for a confrontation. Now he is pretending to be its victim,” the ministry said, Gothamist reported.

Anton Goodman, acting executive director of Rabbis for Human Rights, said the farmers hadn’t reached that land in three years. “No one could have known about this order in advance,” he said. Rabbi Jill Jacobs, the chief executive of the American group T’ruah, was among those detained. “This is an outrageous abuse of power, and part of a systematic, state-backed campaign of ethnic cleansing aimed at driving Palestinians from their land,” she said in a statement. Israeli authorities have rejected accusations of ethnic cleansing.

An illustrated olive tree spreads thick roots around a buried stone house, with roots bridging a deep crack in the earth and rolling hills beyond.

Amy Spitalnick, chief executive of the Jewish Council for Public Affairs, said 33 of those detained were U.S. citizens and that some had been charged with “disturbing the peace.” The State Department told NPR it was tracking the situation but would not comment further, citing privacy.

Settler attacks on Palestinians have risen ahead of Israel’s Oct. 27 election. Last week, Heidi Levine, a Washington Post photojournalist, was injured by masked settlers near the village of Abu Falah, and settlers attacked European diplomats the next day. The police said they had arrested 10 suspects. In July, Representative Ro Khanna, a California Democrat, was briefly detained by Israeli forces during a visit to the West Bank.

Mr. Lander, a former New York City comptroller who is Jewish, is an ally of Mayor Zohran Mamdani, who called for the other detainees to be freed. In June he beat Representative Dan Goldman in the Democratic primary for the 10th District, which covers Lower Manhattan and parts of Brooklyn. Opposition to U.S. military aid to Israel was central to his campaign.

“My constituents don’t want their tax dollars paying for this,” he told NPR before he was detained. In next month’s general election, he faces the Republican nominee, Jennifer Moore.