14 April 1970
The United Nations Special Committee on Apartheid urged a boycott of all South African racist sporting organizations and supported the African bloc’s proposal to exclude the country from both the Munich Olympics and the Olympic Movement itself. Subsequently, on 15 May 1970, the International Olympic Committee (IOC) extended South Africa's ban. This resulted in the country's exclusion from the tragic 1972 Olympic Games in Munich, Germany where eleven Israeli Olympians were murdered by eight Palestinian terrorists who entered the Olympic Village.
References

O’Malley, P. ‘1970’, from Nelson Mandela Centre of Memory, [online], available, at www.nelsonmandela.org.za (Accessed: 12 March 2013)|

Rosenberg, J. ‘History of the Olympics: 1972 - Munich, West Germany’, [online], available at https://history1900s.about.com (Accessed: 12 March 2013)