12 July 1948
For an excellent background history of this complaint by E. S. Reddy, and how it was taken to the United Nations, read article. For chronological details of the early opposition by India to the new apartheid government, read article. To read the actual contents of the Indian government document put to the United Nations in 1948 (Document 2 - Letter dated 12 July 1948 from the representative of India to the Secretary-General concerning the treatment of Indians in South Africa. - A/577, 16 July 1948) , read document.  
References

Enuga Reddy, (2012), ‘INDIA AND THE STRUGGLE AGAINST APARTHEID’, from Muthal Naidoo, 04 August, [Online], Available at www.muthalnaidoo.co.za [Accessed: 11 July 2013]|General Assembly resolution: Treatment of Indians in the Union of South Africa.