The National Union of Students investigated Malia Bouattia over alleged antisemitic comments a year before she was elected the union's president, it has been claimed.

According to the Tab student newspaper, the NUS inquiry took place in early 2015 and found her guilty of misconduct. It concluded that it was "not unreasonable" to regard her comments as antisemitic.

Neither the existence of the inquiry, nor its findings were released, it is claimed.

Ms Bouattia caused anger ahead of her election in April this year for describing Birmingham University, which has a large Jewish student population, as a “Zionist outpost” and referring to “the Zionist-led media”.

Four student unions have already disaffiliated from the NUS in protest, with others set to vote in the next few days.

The Tab says it has seen a letter, dated March 3 2015, which, it claims, was sent by the NUS in response to complaints about alleged antisemitic remarks made by Ms Bouattia in a speech.

The letter said that Ms Bouattia had violated point 9.4 of the NUS Code of Conduct, “acting in contravention of the NUS Equal Opportunities Policies”.

It acknowledged that it was “not unreasonable” for the complainant “to believe that the content of Malia’s speech was antisemitic and therefore in breach of Code of Conduct.”

But, the letter continued, the NUS was “satisfied, based on the evidence and information available… that it was not Malia’s intention to be antisemitic”.

Her actions did “amount to misconduct”, however, and would be dealt with through an “informal warning”, the letter said.

She would be asked to “familiarise” herself with the union’s code of conduct and equal opportunities polices and make a written apology.

A spokesperson for the NUS said: “We can’t comment on individual cases. Our complaints process is confidential.”

Russell Langer, campaigns director of the Union of Jewish Students,said that the letter confirmed that "NUS have previously found Malia Bouattia’s rhetoric regarding Zionism has been antisemitic under its official definition.

"It is also clear that despite having previously been warned over such rhetoric, the NUS President-elect has continued to use similar language.

"Regardless of NUS’ investigation, it is most worrying that although these incidents were well known in the lead up to NUS Conference, delegates still decided to elect her."

He added: "UJS has made it clear that unless she adequately addresses the concerns Jewish students have towards her previous rhetoric then we will be unable to work with her.

"This must include recognising the EUMC definition of antisemitism which is regarded by many Jewish people as a comprehensive definition and was reaffirmed by NUS Conference this year but has previously been described by the now NUS President-elect as 'ominous'."