 A fully elected Legislative Assembly was finally established in 1958 , when Singapore relinquished its colonial status to become a self @-@ governing state . Its powers extended to areas not previously under its purview , such as defence and foreign policy . This situation remained throughout merger with Malaysia in 1963 , and after separation from Malaysia and full independence in 1965 . In the Proclamation of Singapore contained in the Independence of Singapore Agreement 1965 entered into between Malaysia and Singapore , Prime Minister Lee Kuan Yew proclaimed on behalf of the people and Government of Singapore that as from 9 August 1965 Singapore " shall be forever a sovereign democratic and independent nation , founded upon the principles of liberty and justice and ever seeking the welfare and happiness of her people in a more just and equal society " . 
