Absa bank is reportedly threatening to close down the bank account of President Jacob Zuma's wife, Thobeka Madiba-Zuma after unexplained activity in her account.
The Sunday Times reported that the bank had sent her a letter asking her to explain the millions of rands that were passing through her account.
An insider told the newspaper that this was "part of a routine for her to help the bank to understand the source of the monies and the change of behaviour in her account."
"If she doesn't provide the bank with that information it becomes suspicious," the source told the newspaper.
Absa's actions come after it joined other major banks in closing accounts linked with the Gupta family.
It is not clear whether the action against Madiba-Zuma is linked to the Gupta-related controversy with the banks.
The family and their 14 companies, were stripped of their banking privileges and their JSE sponsorships by the four major banks in South Africa, following suspicious banking transactions.
"Revelations that the bank is targeting accounts held by the Zuma family may explain the political pressure that has been put on Absa since last year," the paper reported.
Madiba-Zuma reportedly denied receiving any correspondence from the bank.
"I have no knowledge of Absa's intention to close my account. I have not received anything which has been communicated to me," she told the Sunday Times.