UNRRA was governed by an agreement which had 52 state parties. It was established by the [Agreement for United Nations Relief and Rehabilitation Administration], done at Washington, November 9, 1943. UNRRA was headed by a Director-General, and governed by a Council (composed of representatives of all state parties) and a Central Committee (composed of representatives of the US, UK, China and the USSR).
(Although the UNRRA was called a "United Nations" agency, it was established prior to the founding of the United Nations. The explanation for this is that term "United Nations" was used at the time to refer to the Allies in World War II, having been originally coined for that purpose by Roosevelt in 1942.)