The legal basis of the Bangladeshi provisional government was provided by the proclamation of independence issued on 10 April 1971 , which served as the interim constitution of Bangladesh until 1972 . It declared that Pakistan failed to convene its elected representatives for framing a new constitution on 3 March 1971 ; and instead launched an " unjust and treacherous war " , a reference to the 1971 Bangladesh genocide . As a result , Sheikh Mujibur Rahman , described as the undisputed leader of the 75 million people of East Pakistan , fulfilled aspirations for self-determination by declaring Bangladesh 's independence on 26 March 1971
1971 Bangladesh genocide
1971 Bangladesh genocide
Provisional Government of Bangladesh