The Government Employees Pension Fund (GEPF) this week announced that Maemili Ramataboe, the fund's principal officer, has agreed to the "early expiry of her services" with immediate effect.
Segametsi Serote, the spokesperson for the GEPF, says that a disagreement between the board of trustees and Ramataboe had led to a "parting of the ways".
She says the reason for the disagreement was confidential and had nothing to do with the management of the fund.
Ramataboe was appointed as the principal officer in June 2008, and her term of office would have ended in May next year.
Adri van Niekerk, the former head of the board secretariat (which is responsible for ensuring that the board practises sound governance), has been appointed as the acting principal officer until further notice.
The GEPF is the largest pension fund in South Africa, with about 1.197 million active members, 318 000 pension recipients and net assets under management of R778 billion (as at the end of January this year).