The spokesman for South Africa's polygamous president says Jacob Zuma will be "formalizing his relationship" with his longtime fiancee.

Mac Maharaj said Sunday that 70-year-old Zuma and Bongi Ngema-Zuma will hold a private, traditional ceremony in Nkandla, Zuma's home village in eastern KwaZulu-Natal province this coming weekend. Maharaj said he had no further details.

Ngema-Zuma has acted and been treated like a first lady since Zuma became president in 2009. She is identified in Zuma's official biography as one four spouses, besides Sizakele Khumalo, Nompumelelo Ntuli, and Tobeka Madiba.

Ngema-Zuma has accompanied Zuma on official trips and she oversees her Bongi Ngema-Zuma Foundation, established in 2010 to raise awareness about diabetes.