When Sandra Tamari arrived at Israel's international airport, she received an unusual request: A security agent pushed a computer screen in front of her, connected to Gmail and told her to ‘log in’.

The agent, suspecting Tamari was involved in pro-Palestinian activism, wanted to inspect her private email account for incriminating evidence. The 42-year-old American of Palestinian descent refused and was swiftly expelled from the country.

Tamari's experience is not unique. In a cyber-age twist on Israel's vaunted history of airport security, the country has begun to force incoming travelers deemed suspicious to open personal email accounts for inspection, visitors say.

Targeting mainly Muslims or Arabs, the practice appears to be aimed at rooting out visitors who have histories of pro-Palestinian activism, and in recent weeks, has led to the expulsion of at least three American women.

It remains unclear how widespread the practice is.

However, asked about Tamari's claims, the Shin Bet security agency confirmed she had been interrogated and said its agents acted in accordance with the law.

Israel has a long history of using ethnic profiling, calling it a necessary evil resulting from its bitter experience with terrorist attacks. Arab travelers and anyone else seen as a risk are often subjected to intense questioning and invasive inspections, including strip searches.

The security procedures appear to be getting stricter: Recent searches of journalists at official events have been invasive enough to create a series of mini-uproars and walkouts - a situation that has dovetailed with increasing concerns that the government is trying to stifle dissent.

Diana Butto, a former legal adviser to the Palestinian Authority and a fellow at the Harvard Kennedy School of Government, said the policy of email checks, once used sporadically, appears to have become more widespread over the past year.

Butto said she has led three tour groups to the region over the past year, and in each case, at least one member of the group was asked to open their email. She said Muslims, Arabs and Indians were typically targeted, and in most cases, were denied entry.

Butto said agents typically want to see people's itineraries, articles they have written or Facebook status updates.

"The problem is there's no way to honestly say you're coming to visit the West Bank without falling into some type of security trap," she said. "Either you lie and risk being caught in a lie, or you tell the truth ... and it's not clear whether you'll be allowed in."

Tamari, who is from St. Louis, said she arrived in Israel on May 21 to participate in an interfaith conference. She described herself as a Quaker peace activist and acknowledged taking part in campaigns calling for boycotts and divestment from Israel.

Given her activism, Tamari said she expected some security delays. But she was caught off guard by the order to open her email account. She said the agents discovered her address while rifling through her personal papers.

"That's when they turned their (computer) screens around to me and said, 'Log in," she said. When she refused, an interrogator said, "'Well you must be a terrorist. You are hiding something.'"

Tamari said she was searched, placed in a holding cell and flown back to the U.S. the following day. "The idea that somebody my age, a Quaker, on a peace delegation with folks from the U.S., would be denied entry – that never crossed my mind," she said.

Najwa Doughman, a 25-year-old Palestinian American from New York City, said she underwent a similar experience when she arrived for a one-week vacation on May 26.

A female interrogator ordered Doughman to open her Gmail account, threatening she would be deported if she didn't.

"She typed in gmail.com and she turned the keyboard toward me and said, 'Log in. Log in now,'" Doughman recounted. "I asked, 'Is this legal?' She said, 'Log in.'"

She said the agent searched for keywords like ‘West Bank’ and ‘Palestine’ and made fun of a chat in which Doughman talked of reading graffiti on Israel's West Bank separation barrier.

"After she read a bunch of stuff, humiliating and mocking me, I said, 'I think you've read enough,'" Doughman said, adding that agents jotted down names and emails of her friends as they inspected her chat history.

Doughman's traveling companion, Sasha Al-Sarabi, said agents pulled her aside and checked out her Facebook page.

Both women said they were approached because of their Arab family names, and were repeatedly asked about the nature of their visit, and whether they planned to go to the West Bank and participate in anti-Israel demonstrations.

While acknowledging she belonged to Palestinian activist groups when she was in college, Doughman said she insisted the one-week visit was purely for a vacation.

"The interrogator asked me, 'Do you feel more Arab or more American? ... Surely you must feel more Arab," Doughman said. "I told her I was born in the U.S. and studied there, but she didn't like my answer."

After hours of questioning, both women were told they would not be allowed in. They said they were subjected to strip searches, placed in a detention center and sent back to the U.S. the following day. Doughman said they weren't allowed to call the U.S. Embassy.

American Embassy spokesman Kurt Hoyer said the embassy does not comment on specific cases. But he said the embassy is ‘usually’ contacted whenever an American citizen is not allowed to enter Israel, or any other country.

The embassy typically remains in contact with local authorities throughout the process until a decision on entry is made.

He said the U.S. stresses to all governments ‘to treat American passport holders as Americans, regardless of their ethnic origin ... At the same time, any sovereign nation has the right to decide who to let in, and not to let in’.

Israel has become increasingly strict following a series of run-ins with international activists in recent years, highlighted by a deadly clash two years ago between Israeli naval commandos and a flotilla trying to break Israel's naval blockade of the Gaza Strip. Both sides accused the other of provoking the violence in which nine Turkish activists were killed.

Since then, Israel has prevented international activists from arriving on similar flotillas as well as a pair of ‘fly-ins’ by pro-Palestinian activists. Israeli officials acknowledge they used social media accounts, such as Facebook and Twitter, to identify activists ahead of time and prevent them from boarding flights to Israel.

Emanuel Gross, a law professor at Haifa University, said such a practice would seem to be illegal in Israel.

"In Israel, you need a search warrant to go into somebody's computer," he said. "I'm skeptical that the security guards asked a judge first for a warrant and I'm skeptical that a judge would give it."