Jewish representatives say they are “appalled” at online anti-Semitism from current and would-be national student leaders, and have urged candidates vying for senior positions at the National Union of Students to “step down”.

The angry reaction came after an investigation by The Independent showed Sean O’Neill, a candidate for the NUS National Executive Council, writing about Jews on Twitter in 2012, signing off with the hashtags #heilhitler and #fuckslutskilljews.

Elsewhere, with the union’s LGBT+ Officer Noorulann Shahid is shown saying they “laughed out loud” at a parody video showing miserly Jews with big noses. Again, the comments were made in 2012. Both have apologised.

The investigation came at the start of the NUS annual conference this week, and a week after Ali Milani, who is running for NUS vice-president, was accused of “deeply anti-Semitic” remarks in tweets sent five years ago, for which he has apologised.

It was also revealed that, during her time at Birmingham University, NUS President Malia Bouattia helped promote Caryl Churchill’s controversial ten-minute play ‘Seven Jewish Children’. It was written about Gaza in 2009, but has been accused of being anti-Semitic.

The revelations will do nothing for Jewish students’ confidence in the NUS or Bouattia, who has been cleared of three counts of anti-Semitism. She is a known critic of Israel, who has been criticised for her reaction to Jewish students’ concerns about anti-Israel sentiment on campus.

Josh Nagli, campaigns director at the Union of Jewish Students, said he was “appalled by these absolutely disgraceful comments, all of which are extremely offensive to Jewish students.”

He added: “The regularity of anti-Semitic comments being made by candidates is exceptionally worrisome and shows complete disregard for the welfare of Jewish students, as well as for the anti-racist, anti-fascist values that NUS and many of these individuals claim to uphold – particularly when those comments invoke the memory of the Holocaust.”

Nagli said the candidates concerned “should do the right thing now and step down from their elections,” adding: “These comments should not be seen in isolation; they reflect a wider culture of wilful tolerance towards anti-Semitism from members of the far left of the student movement that has been present for a number of years.”

Jewish students say they are “still waiting for an adequate apology” from Bouattia, who is accused of showing “complete disdain towards anti-Semitism”.