Mr Mashaba also said the government’s “pro-poor agenda” has been “undermined, criticised and rendered nearly impossible” by the DA.

Mr Mashaba was seen as a key ally of the party’s first black leader, Mmusi Msimane, in his efforts to increase support among black voters.

But the DA’s share of the vote dropped in the May general election after conservative whites abandoned the party, and Ms Zille’s return to a senior post in the party is seen as an attempt to regain their support.

Mr Mashaba said he would step down next month, raising questions about whether the DA would be able to retain the mayoral post in Johannesburg.