More than 400 alumni and other protesters have signed a letter sharply criticizing Friends' Central School for canceling a Palestinian speaker and suspending the two teachers who invited him, calling the actions "appalling" and "a sad betrayal" of free speech and open discussion on the Wynnewood campus.

"As a Quaker school with longstanding commitments to inclusivity, Friends' Central School should be a bulwark against efforts to bully and silence voices for peace and justice," states the letter drafted this week by Lara Langer Cohen, a 1995 graduate who is an associate professor of English at Swarthmore College and a faculty colleague of the canceled speaker, Sa'ed Atshan.

Cohen's online petition calls on Craig N. Sellers, the head of school, to reinvite Atshan and reinstate the teachers, Ariel Eure and Layla Helwa. A second letter started by 2012 graduate Bill Fedullo, a first-year law student at the University of Pennsylvania, is circulating on Facebook.

"We're not an anti-Zionist group," said Fedullo, noting that many of the alumni joining his Facebook group are Jewish. "We just don't think that the high school should be censoring this kind of inquiry, especially from an academic who has a genuine commitment to peace in the region."

Atshan's speech to the school's Peace and Equality in Palestine Club, scheduled for last Friday, was called off after some Jewish parents objected to his past support for punitive economic measures against Israel over the occupied territories. The letters, following student protests and walkouts, are the latest sign that the controversy over the cancellation and the subsequent suspension of the two teachers will not be blowing over any time soon.

The episode is drawing national media attention as a symbol of growing unrest on high school and college campuses over free speech surrounding the Israel-Palestine conflict.

Indeed, the dispute heated up on a day when the Middle East was prominent in political discussion, as Israeli Prime Minister Benjamin Netanyahu visited the White House and the Trump administration signaled that the United States would no longer insist on a "two-state solution" as part of a peace accord.

At the City Avenue school, students have plastered the locked door to the classroom of English teacher Eure, 25, with Post-It notes of support. Meanwhile, attorney Mark D. Schwartz, who is representing the teachers, has lodged a formal letter of complaint with Sellers and Phillip Scott, clerk of the board of trustees. It argues that the two women's paid suspension violates the mission and values of the Quaker school to promote open discussion and diversity of thought.

Schwartz's three-page letter also complains that Sellers' action harassed and discriminated against Eure and Helwa and that any decision to place the teachers on administrative leave would have to come from the board of trustees, not the head of school. Sellers, he wrote, violated the terms of the school handbook.

"It's clear, at least to me, [Sellers is] in violation of basic tenets of the school, and I hope after the trustees give him the due process he did not give my clients, they take appropriate action, up to and including his removal," Schwartz said Wednesday.

On Tuesday, Friends' Central sent parents a new letter from Sellers and Scott defending the school's actions, and saying that Atshan's appearance before the Palestinian club was not canceled but "paused" and that the teachers were sanctioned for ignoring "explicit directives."

"There was a fundamental breakdown in process," the letter said. "We simply did not approach this very sensitive topic with adequate community dialogue." It stated the board is creating a task force that will include current parents and other community members to "determine how we will move forward."

To alumni critics such as Cohen, any solution must involve reinviting Atshan, a native Palestinian and a Quaker who now teaches in the Peace and Conflict Studies department at Swarthmore, which is also his alma mater.

"People feel this doesn't comport with their sense of the school and the school's values, and is a betrayal of the values that they learned there," said Cohen, who attended Friends' Central for 13 years.

She said her petition is winning support from alumni, academics, and interested Quakers because they "still had a sense of the school as a place to be modeling a commitment to social justice and critical inquiry and support of that. So this really, really took them by surprise."