Democratic Alliance (DA) leader Mmusi Maimane has admitted in a newsletter that his statement – that five former DA members who resigned as Cape Town councillors last week were implicated in incriminating forensic reports – was incorrect.

City council chief whip Shaun August announced his resignation during a dramatic council meeting on Thursday, shortly after embattled Mayor Patricia de Lille addressed the council for probably the last time.

De Lille railed against her detractors during the speech and dismissed the allegations against her, documented in a new independent report commissioned by the City, "as racist, bully attacks".

August's resignation was followed by those of mayoral committee members Suzette Little and Siya Mamkeli, as well as councillors Greg Bernado and Thulani Stemela.

After their boardroom exit, they addressed the media and claimed racial victimisation in the party was one of the primary reasons for their exit.

In his newsletter Bokamoso, Maimane wrote on Friday that playing the race card was used to escape accountability. He also said the five were "allegedly implicated in tender irregularities" by the report, compiled by law firm Bowmans.

He also said at a press conference in Limpopo on Friday that the five were implicated in wrongdoing in the City.

On Saturday and Sunday, August demanded an apology from Maimane.

"I'm stunned to at how you arrived at this conclusion as none of our names are mentioned in any of the reports," August wrote in a social media post.

"If you have any integrity left or an inch of backbone, you would do the right thing and apologise immediately for spreading misinformation (sic)."

On Monday, Maimane re-released his newsletter, but added a disclaimer which read: "Fridays Bokamoso contained a factual inaccuracy regarding the role of the five former DA councillors in Cape Town, an error for which we apologise. Please find below the corrected version."

In Friday's edition of the newsletter, Maimane wrote: "For five Cape Town councillors, the DA wasn't a racist party last month. But now that a credible forensic investigation by credible legal firm has allegedly implicated them in tender irregularities, the DA is suddenly a racist party."

In Monday's edition, this paragraph read: "For five Cape Town councillors, the DA wasn't a racist party last month. But now that they've been shown to be the most ardent defenders of maladministration, despite evidence which has now been confirmed by a credible forensic investigation, the DA is suddenly a racist party."

Maimane previously indicated that his lawyer would deal with August's demand. He again said at a press briefing on Eskom on Monday morning that he wanted his lawyers to deal with the matter.

"There's a report that finds challenges in the municipality and now people want to resign. They must be running away from something."

The council's adoption of the report means De Lille, mayoral committee member Brett Herron and some officials would be subjected to disciplinary investigations by the City or criminal investigations by the police. De Lille and Herron have criticised the report and pleaded their innocence.

However, the five renegade councillors are not named in the report, which was also pointed out by DA Cape Metro leader Grant Twigg on Thursday evening after the council meeting.