Suzette Little says she resigned as a DA councillor because she could no longer tolerate the double standards and strong-arm tactics used by the party.
Little is one of five City of Cape Town councillors who tendered their resignations on Thursday.
She resigned from the party and from the council.
She claims that councillors were forced to agree to an investigation into outgoing Cape Town Mayor Patricia De Lille.
Little says DA leader Mmusi Maimane threatened their jobs if they didn't toe the party line in previous council votes.
She alleges that the deputy chairperson of the DA's federal council, Thomas Walters, was appointed to keep tabs on council members and conduct surveillance on their social media.
Little claims council members in favour of De Lille were specifically targeted.
She says that De Lille and her perceived supporters within the caucus were victimised.
DA chief whip Shaun August also resigned on Thursday, saying he can no longer tolerate what's happening to De Lille.
He resigned as whip, councillor and DA member.
Other councillors who resigned in support of the outgoing mayor include Mayco member Siyabulela Mamkeli and ward councillors Greg Bernardo and Thulani Stemele.
Thomas Walters has been appointed by the party to watch those folks that are in favour of the mayor, to scan their Facebooks and make sure that they don't post anything that's in favour of the mayor.— Suzette Little, former DA councillor
It's that type of treatment that I've had enough of.— Suzette Little, former DA councillor
The party has spent a lot of time and money into investigations to prove that the mayor is corrupt.— Suzette Little, former DA councillor
The party took a stance when they came to the caucus and instructed the caucus how to vote.— Suzette Little, former DA councillor
We were instructed - not having any knowledge or any papers before us - how to vote.— Suzette Little, former DA councillor
Mmusi made it clear that if we don't vote the way he instructs, we will be fired.— Suzette Little, former DA councillor
I was not voted in for a salary.— Suzette Little, former DA councillor
The party allowed people to do defame her [De Lille] and did nothing about it.— Suzette Little, former DA councillor
I'm loyal to ethics... I supported the DA and I believed in what they stood for, unfortunately, my sentiments have changed.— Suzette Little, former DA councillor
#CTCouncil Little: "The same rules that apply to my white colleagues, don't apply to me." LD— EWN Reporter (@ewnreporter) October 25, 2018
#CTCouncil Little says Selfe forced councillors to agree to an investigation into De Lille - they were not given a chance to consider the documents. LD— EWN Reporter (@ewnreporter) October 25, 2018
Listen to Suzette Little in conversation with CapeTalk's John Maytham: