She was sharing a August 2018 post that claimed the Israeli government operated an app which urged people to condemn Jeremy Corbyn for antisemitism.
The app, called Act.IL, asked users to comment under a Facebook post condemning anti-Israel sentiment frequently expressed by Labour members since Mr Corbyn’s appointment as leader, which it suggested was designed to “hide deeper antisemitic feelings”.
The Act.IL website says the app was created with the aim of using social media to combat the boycott, sanctions, and divestment movement, and the delegitimisation of the State of Israel.
It was a joint venture between the Israeli-American Council and the Israel-based Interdisciplinary Center (IDC), the Jerusalem Post reports.
Karen Pollock, the chief executive of the Holocaust Educational Trust, accused Ms Whitson of “sharing antisemitic conspiracy theories”.
Human rights barrister Adam Wagner tweeted: “Human Rights Watch has been studiously silent about what one mighy think was an important human rights issue - antisemitism in the UK. Breaks its silence by promoting this story.”