Simone Zimmerman, an American Jewish activist, was held by the Shin Bet security service at the border between Israel and Egypt for at least three hours on Sunday evening, Israel's Immigration Authority confirmed.

Shin Bet agents asked Zimmerman which places she had visited in the West Bank and what she thought of Prime Minister Benjamin Netanyahu, she said.

Zimmerman is a founding member of IfNotNow, a movement to end the American Jewish community's support for the Israeli occupation.

While still detained at the Taba border crossing, Zimmerman wrote on Twitter that she and fellow activist Abby Kirschbaum were being questioned only about their political views and activities related to Palestinians. According to Zimmerman, among the first things she was asked were: "Why did you come here to work with Palestinians? Why not with Jews?"

Kirschbaum was asked about which protests against Israeli policy she had attended in the Palestinian territories and with which organizations, Zimmerman said. She was also asked if she wished to travel to Gaza and whether she had been at violent demonstrations – and what she thought of Netanyahu.

In 2017, Zimmerman, who resides in Israel and has a work visa, published a video criticizing an Israeli law barring entry to foreigners who support boycotting Israel or its West Bank settlements.

Zimmerman briefly served as the Jewish outreach coordinator for Bernie Sanders' 2016 primary campaign before being fired over an old Facebook post surfaced in which she stated that Netanyahu had sanctioned murder.

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The Shin Bet did not immediately respond to a request for comment.

Zimmerman's questioning came less than a week after an Israeli citizen who lived in the U.S. for several months was detained by Shin Bet agents at Ben-Gurion International Airport in Tel Aviv for a "cautionary conversation" because of his involvement in left-wing organizations.

In July, a prominent Jewish-American philanthropist was delayed for questioning at Ben-Gurion Airport after a pro-Palestinian pamphlet was found in his suitcase.

"It is now beyond doubt that the Netanyahu government has turned its border crossings into interrogation chambers," said Daniel Sokatch, the CEO of the New Israel Fund, reacting to the reports on Simone Zimmerman's interrogation.

"The government is demonstrating once again that the test for entering the country is a political one - either you agree with Prime Minister Benjamin Netanyahu's ultra-right wing coalition or you're subject to questioning, intimidation, or refusal. This may be legal, but it's morally unacceptable and anti-democratic," he added.

Yael Patir, the Israel director of left wing pro-Israel lobby J Street, said in response to Zimmerman's detention: "A country whose security services detain people to check the level of their sympathy to its prime minister, is a country already in the dangerous midst of a slippery slope." According to Patir, "the multitude of cases in which political and human rights activists are detained at border crossings requires an explanation. We demand Shin Bet head Nadav Argaman explain to the citizens of Israel and those who wish to visit why his people detain, interrogate and show an interest in [their] political preferences."