In particular anti-semitism is usually associated with the right, but it has a pretty long tradition on the left as well. The 60s in the communist block were a good display of that, but also the 40s in France (Tony Judt wrote a couple books about that, e.g. the French Communist Party, as depicted in The Burden of Responsibility: Blum, Camus, Aron, and the French Twentieth Century).