Outa has been battling to get Mineral Resources Minister Mosebenzi Zwane to provide assurances that the funds are intact.
"We want the rehabilitation account frozen because we are concerned that this money could disappear," said Outa chief operating officer Ben Theron.
"The account must be frozen until assurances are given by Zwane that the ministry will appoint decent trustees."
He said indications were that Ronica Ragavan, CEO of Gupta-owned Oakbay, ran the fund. Theron said this was "unacceptable".
Bloomberg news agency reported that the Bank of Baroda had total assets of R2.76-billion in South Africa by the end of June, as against R4.36-billion a year earlier when the Guptas moved their funds to the Indian-based lender.