In 1945, Britain and France were rivals for control over the Middle East, and the former hoped to keep the Land of Israel under the authority of a friendly Arab ruler, while expanding its influence into the French protectorate of Syria. The British had at the time recruited Jamil Mardam Bey, a senior minister in the Syrian government, to work for them. When French intelligence caught him, they managed to turn him to their side. Meir Zamir, drawing on newly revealed archival materials, discovered something surprising about this relationship:
It all began in October 1945, when the French encountered a new problem. Mardam had been appointed Syria’s ambassador to Egypt and its envoy to the Arab League headquarters in Cairo, but the French had a hard time utilizing him there without arousing suspicion. The solution was to recruit Eliahu Sasson for the mission of relaying the information provided by Mardam.
Sasson, who was then the head of the Arab division of the Jewish Agency’s political department, had been appointed by the Agency’s head David Ben-Gurion in February 1945 to coordinate cooperation with French intelligence. The Syrian-born Sasson knew Mardam and had met with him in 1937, when the latter had served as prime minister, [a position to which he would later return]. The French, who were well acquainted with Sasson and thought highly of his operational capabilities, began to collaborate with him in handling Mardam.
From July 1945, Ben-Gurion had prepared for the possibility of an attack by the Arab states should the Jewish state declare its independence. But the information from Mardam turned the spotlight elsewhere. Ben-Gurion learned that the immediate threat to the establishment of the Jewish state lay not in an attack by Arab armies, but rather in the plan of British military commanders and intelligence agencies in the Middle East to thwart that development by various other means. These included declaring the Haganah militia a terrorist organization and disarming it, and implementing the “Greater Syria plan,” under which a limited Jewish entity would be created in Mandatory Palestine, but not an independent state.
Read more on Haaretz: https://www.haaretz.com/israel-news/.premium.HIGHLIGHT.MAGAZINE-revealed-syrian-prime-minister-was-a-double-agent-who-spied-for-zionist-leaders-1.9305783