On the occasion of the 1929 riots, the Jewish Communists were split between those who sympathised with victims of the massacres, and others who, like the Arab Communists, considered the moment to be one of an Arab revolt against the British occupation, land seizure and the pauperisation of the peasantry. Based in Haifa, where he supervised the Party's local branch, Sidqi maintained regular contacts with Sheik Izz ad-Din al-Qassam, and defined the latter's death in 1935 as one of martyrdom. The Comintern had instructed the Palestine Communist Party to Arabise as early as 1924, without much success. One of the tasks the Party assigned to Sidqi was to undertake this Arabisation. The Palestine branch of the party was largely dominated by Jews with socialist tendencies and was suspected of having in its ranks militants with crypto-Zionist sympathies. In 1930, Sidqi was picked up by the British police in Jaffa and sentenced to 2 years imprisonment, which he served in Jerusalem, Jaffa and Akka. His elder brother Ahmad, who had also studied with him at KUTV, was the chief witness for the prosecution. In Sidqi's recollection, Ahmad is described as fragile and being coerced into confessions by beatings. British reports cast him as a police informer, who provided extensive details of Comintern contacts and training. Towards the end of 1932, on his release from prison, where he made the acquaintance of Abu Jilda, the 'Dillinger of the desert,' the Party ordered him to contact Awni Abd al-Hadi in order to begin to coordinate with the Istiqlal Independence Party. As British surveillance intensified, the Communist Party smuggled him abroad in June 1933 to Paris where he assumed the editorship of the Comintern's Arabic-language journal, "The Arab East". The French authorities subsequently arrested him and had him deported back to Palestine. He later dated his opposition to Nazism to this period – Hitler assumed power in 1933.