Labour was accused of “once against” failing to match pledges on zero tolerance of anti-Semitism with action after a Labour activist who faced a disciplinary process for claiming Jews were “chief financiers of the sugar and slave trade” had her suspension lifted.

Jackie Walker, vice-chair of steering group of Momentum and of the South Thanet Labour Party, made the comments in a social media post.

She is the first member suspended in recent weeks during Labour’s anti-Senitism scandal to be reinstated following an investigation – leading a small number of party members to take to social media vowing to end their membership.

Walker said: “I am glad this investigation has fully cleared me of any wrongdoing. I am not a racist, but I robustly defend my right and the right of others to speak openly and frankly about matters of grave political and historical importance.”

Ms Walker’s solicitor, Martin Howe, said: “The danger with cases like this is that genuine debate and free speech has been silenced by the chilling effect of unfair and inaccurate allegations of anti-Semitism against a person who has fought against racism, in all forms, all her life.”

The Jewish Labour Movement tweeted: “Jackie Walker repeated an anti-Semitic slur. She showed no contrition. The outcome of this process shows, once again, that the political rhetoric of zero tolerance on anti-Semitism is not matched by action. This is why we are proposing changes to party rules.”

Jonathan Arkush, president of the Board of Deputies, said: “We find it remarkable that Jackie Walker has been readmitted to the Labour Party without any disciplinary sanctions and by a process completely lacking in transparency.  We are very disturbed by the way she has reacted with unrepentant and defiant statements.”

During an interview this week, she said: “I don’t have an apology to make. I’m saddened if I’ve upset people, but sometimes when we’re talking in political speech we upset people, and these issues are very upsetting.”

The CST’s Dave Rich described the suggestion that Jews played a leading role in the slave trade as a “modern anti-Semitic myth”, adding: “The consequence of all this is that it is now OK for Labour members to say that Jews were behind the slave trade, and that their living descendants owe some kind of debt as a result. This anti-Semitic myth has become part of the Left’s conversation about Jews. This is how antisemitism becomes normalised, and how Jews get squeezed out of the Labour Party.”