Western Cape Premier Helen Zille will face a disciplinary process for her tweets about colonialism, DA leader Mmusi Maimane said on Thursday.
Speaking on 702, following an uproar over the tweets, he distanced himself from them and said they were unacceptable.
She had breached the party's social media policy, he said.
"It has been referred to a disciplinary process. I have come out as a South African and condemned it. The wording is indefensible."
He said a member who breached the party's social media policy could be fined, or lose their membership.
Earlier, Zille tweeted: "Getting onto an aeroplane now and won't get onto the Wi-Fi so that I can cut off those who think EVERY aspect of colonial legacy was bad."
"For those claiming legacy of colonialism was only negative, think of our independent judiciary, transport infrastructure, piped water etc," she wrote.
She later apologised.
For those claiming legacy of colonialism was ONLY negative, think of our independent judiciary, transport infrastructure, piped water etc.— Helen Zille (@helenzille) March 16, 2017
Would we have had a transition into specialised health care and medication without colonial influence? Just be honest, please.— Helen Zille (@helenzille) March 16, 2017
I apologise unreservedly for a tweet that may have come across as a defence of colonialism. It was not.— Helen Zille (@helenzille) March 16, 2017
Twitter users were not impressed with Zille's tweets.
"Rape may be bad but sometimes it produces good children" - Helen Zille logic pic.twitter.com/nVlf694uGi— Shaka Zulu (@IAmShakaZulu) March 16, 2017
No Helen Zille, colonialism did not bring 'development' to Africa. It brought oppression, exploitation, racism, poverty, etc, etc, etc. pic.twitter.com/mz9oqp19df— Ulrich J van Vuuren (@UlrichJvV) March 16, 2017
Maimane said that "if we want to build a South Africa for all, we need to all come around and understand the history and the pain of all South Africans. It's not a question of saying if you are black you must be anti-colonialism, and if white in any other way. It is to say all of us must be quick to denounce the evils of the past because all of us need to join hands to build a prospective future together."
DA MP Dianne Kohler Barnard's party membership was terminated at the end of October 2015 after she shared journalist Paul Kirk's Facebook post.
"Please come back PW Botha — you were far more honest than any of these [African National Congress] rogues, and you provided a far better service to the public," it read.
At a disciplinary hearing, she pleaded guilty to breaching the party's social media policy and bringing it into disrepute.
Her expulsion was lifted following an appeal. The party decided to keep her in her position until the end of the fifth Parliament, on condition that she not be found guilty of any transgressions during that period.