The Democratic Alliance, South Africa’s biggest opposition party, said it has placed the mayor of the municipality that includes the capital, Pretoria, on leave.
Stevens Mokgalapa, the mayor of Tshwane, was the subject of a leaked audio tape in which he allegedly disparaged government officials in a conversation with a mayoral council member and indulged in sex acts.
The party said the action had been taken against him in a statement on Tuesday.
The Economic Freedom Fighters, the second-biggest opposition party, is pushing for a vote of no-confidence in the mayor.
The scandal is another blow for the DA.
After a strong performance in municipal elections in 2016, it formed alliance to put in place party officials as mayors of Pretoria, Johannesburg and Port Elizabeth.
Since then its Port Elizabeth Mayor has been ousted and its mayor of Johannesburg, Herman Mashaba, quit together with party leader Mmusi Maimane after disputes following a fall in support in national elections this year.