The Democratic Alliance announced on Saturday that it had suspended its former leader and current Western Cape premier Helen Zille, pending the outcome of her disciplinary hearing.
Party leader Mmusi Maimane led a briefing where he made the announcement.
"It has become evident that Helen Zille and I hold fundamentally different attitudes about the mission DA must accomplish in 2019," said Maimane.
Maimane is quoted on the party's Twitter account, saying that he had asked Zille to apologise for the damage that she has done and she declined.
Zille was charged by the DA in March for "bringing the party into disrepute and damaging the party", after she published a number of tweets where she said colonialism was not all negative.
One of her tweets read: "For those claiming legacy of colonialism was ONLY negative, think of our independent judiciary, transport infrastructure, piped water etc."
A second tweet read: "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."
The tweets sparked widespread public outrage from senior members of the DA, including party leader Mmusi Maimane, and the public alike.
After the outrage over her tweets Zille was quoted as saying: "Of course colonialism had a diabolical impact worldwide, including South Africa. That was the very premise of my tweets. Anyone who read them without a personal or political agenda would have understood that. If you say the consequences of something were not only negative, you are saying most were negative."
He went on to accuse Zille of undermining what the party is trying to achieve.
Maimane said a notice of suspension will be served on Zille.
She currently holds no position in the party and remains the premier of the Western Cape.