Tshwan mayor Stevens Mokgalapa and MMC for Transport Sheila Senkubuge during a media briefing. File picture: Thobile Mathonsi/African News Agency(ANA)

Pretoria - The DA said on Sunday it had launched an internal investigation into "the serious allegations" made against Tshwane Executive Mayor Stevens Mokgalapa and Member of the Mayoral Committee (MMC) for transport Sheila Senkubuge.

This comes after an audio clip was widely distributed on Sunday allegedly of Mokgalapa having sex with Senkubuge apparently in her office while discussing colleagues and calling them names.

The scandal dubbed #SexInTheCity trended on social media on Sunday with many calling for the mayor to step down.

In a statement on Sunday, the DA said its political leadership would meet with Mokgalapa while the DA’s Federal Legal Commission has been tasked to conduct an internal investigation into the matter.

Mokgalapa has laid charges of extortion and invasion of privacy against some known and unknown individuals at the Brooklyn police station as well as with the Hawks, the DA said in a statement.

According to The Citizen, Mayoral spokesperson Omogolo Taunyane said the clip was being used "as a tool to blackmail and extort undue favours from the City of Tshwane".

Mokgalapa was quoted as saying: “We have been aware of the existence of this audio recording for a few days and threats to release the recording have been communicated to us via an intermediary wherein certain demands have been made.”