Former Democratic Alliance (DA) parliamentary chief whip Douglas Gibson is the latest leader to come out in support of party leader Mmusi Maimane.

It comes in the wake of the spat between Maimane and his predecessor Helen Zille over tweets, which now threaten to divide the party.

Pressure has been mounting for Maimane to take decisive action against Zille. The Western Cape premier is facing a suspension over tweets defending certain aspects of colonialism.

"One thing Helen mustn't forget is that when somebody like Steve Hofmeyr becomes your biggest fan perhaps you are on the wrong track," said Gibson, who has described this as devastating.

The former leader, who spoke at length about Zille's achievements - first as a journalist and then as a leader of the main opposition party - said she had gone completely "haywire" with her tweets.

"She seems deaf to the situation in South Africa; the DA is no longer a small party representing one racial group," he told News24 on Tuesday.

He added that the DA needed to show that it was capable of being sensitive to the ideas, feelings and emotions of everyone it represented.

Gibson also slated Zille for making Maimane's job as party leader difficult.

"My appeal is for her to listen to Mmusi [Maimane], to listen to the many of our black public representatives, who adore her and feel she had done a wonderful job as a leader. Just listen to them, and see if you can't soften your attitude and your approach," said Gibson.

'Doing damage to herself, DA, and country'

He also rubbished Zille's praises of the colonial system's achievements.

"Any government in power for 20, 30 or, even 40 years, leaves a legacy of houses built and things done," he said.

Gibson also said Zille's use of Singapore as a shining example of positives of colonialism was incorrect.

"It's not because of colonialism that Singapore is one of the biggest economies in the world today, or one of the most developed. They did all of that after the colonial period and after the world war, where they were under the occupation of the Japanese," he said.

No sensible senior politician in South Africa would say apartheid had its positives, because that would be offensive, he said.

Gibson also told News24 that he had communicated with Zille over the scandal.

"She stuck to her point, and I stuck to mine," he said.

"I am heartbroken that she has gotten herself into this situation which is doing damage to her, doing damage to the DA and, in the final event, doing damage to South Africa."

Zille has continued to defend the contents of her tweets, even claiming that it's a similar stance taken by people like former president Nelson Mandela and several academics.

Her disciplinary hearing is set to start on Friday.