South Africa's main opposition party has formally charged its former leader with misconduct after a series of social media posts where she suggested colonialism brought benefits to the country.

Helen Zille, the ex-head of the Democratic Alliance (DA) party and the current premier of the Western Cape province, could be expelled for last month's tweets, which prompted public outcry from opponents and those within her own party.

"For those claiming legacy of colonialism was ONLY negative, think of our independent judiciary, transport infrastructure, piped water," Zille had written.

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In a statement, DA leader Mmusi Maimane on Sunday said Zille had "violated the party's federal constitution by acting in a manner which has brought the party into disrepute".

He also told reporters that disciplinary proceedings had begun against Zille, but she would not be suspended during the investigation.

"Our party has always stood for the principle of freedom of speech. This case is not about freedom of speech. Our party has stood for South Africans from all walks of life," Maimane said.

"People can express a view but does that view do damage or harm to the interests of the organisation, which is what this is," he added.

Zille, who apologised for the tweets in mid-March, responded to the charges on Twitter, saying: "I have only one comment: I will abide by due and fair process of SA and DA constitution and the rule of law".

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The DA, which won 22 percent of the vote in 2014's general election, has been gaining popularity and trying to shed its image as a "white" party before 2019's presidential election.

It promotes itself as a liberal equal-opportunity party, but efforts to broaden its appeal among black voters have been hurt by social media scandals, and the party has struggled to present itself as a credible alternative to the ruling African National Congress (ANC).

The ANC's Western Cape office said in a statement that for black members of the DA "uncertainty remains on where the party stands on racism and on the treatment of white and powerful leaders.



"Maimane has not shown the same passion in putting South Africans first above Helen Zille who single-handedly put him where he is," it said. "The DA should have suspended Helen Zille as premier."

'Strong case'

If the DA upholds the misconduct charge against Zille, sanctions could include temporary suspension, a fine of up to $3,700, community service or permanent expulsion from the party.

Maimane said that there is "preliminary evidence that there is a strong case to be made".



"I've got to build an organisation that reflects South Africans. In that instance, Premier Zille has the right to answer," he said.

He added that it would be "incorrect" to say Zille is racist, saying "that's not the person I know."

South Africa was colonised by the Dutch and British for about 300 years. The country then experienced white-minority rule under apartheid, which ended in 1994.

Racial tensions, however, have continued to endure in the years after apartheid.