On his release, Zygielbojm was made a member of the Jewish Council, or Judenrat, which the Nazis had appointed. The Nazis ordered the Judenrat to begin the creation of a ghetto within Warsaw. Because of Zygielbojm's public opposition to the order, his fellow Bundists feared for his safety and arranged for him to leave. In December 1939, Zygielbojm reached Belgium. Early in 1940, he spoke before a meeting of the Labour and Socialist International in Brussels and described the early stages of the Nazi persecution of Polish Jewry.