South Africa's leading opposition party announced on Sunday that it has filed a misconduct claim against a provincial leader over a controversial tweet.

Helen Zille, the current premier of the Western Cape province, and former head of the leading opposition party Democratic Alliance (DA), faces possible expulsion from the DA for tweeting last month that not everything about the country's colonial past was bad. 

"For those claiming legacy of colonialism was ONLY negative, think of our independent judiciary, transport infrastructure, piped water," she wrote on Twitter last month.

DA leader Mmusi Maimane said at a press briefing in Cape Town that disciplinary proceedings had begun against Zille, but that she would not be suspended during the probe.

"Our party has always stood for the principle of freedom of speech. Our party has stood for South Africans from all walks of life," he said. "People can express a view but does that view do damage or harm to the interests of the organization, which is what this is."

Zille is a former journalist and an anti-apartheid activist, but her tweet renewed questions about the DA party's commitment to the fight against racism.

The DA won 22 percent of the vote in the 2014 general election, and has been gaining popularity as it tries to shed its image as a "white" party.

Zuma is the target

But efforts to broaden its appeal among black voters have floundered amid social media scandals at a time when the party has struggled to present itself as a credible alternative to the ruling African National Congress (ANC).

"For Democratic Alliance black members, uncertainty remains on where the party stands on racism and on the treatment of white and powerful leaders," the ANC's Western Cape office said in a statement.

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

Maimane said during a press conference in Cape Town on Sunday that the DA remains resolute in its overriding goal to defeat embattled president Jacob Zuma, who has been mired in allegations of corruption and incompetence, in the next election in 2019.

"We seek to bring all South Africans together behind the vision of a united, non-racial future, under the Constitution, with a growing economy," Maimane said. "We are fast running out of time to save our country from the clutches of the Zuma administration. Now, more than ever, we need to push on in removing Zuma from power."

bik/rc (AFP, DA)