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South Africa's main opposition party called a march Tuesday to make a point about economic policy, but ended up facing rock-throwing counter-protesters in scenes that illustrated that democracy and traditions of political tolerance are still young 18 years after apartheid was toppled.

Democratic Alliance leader Helen Zille led the march of hundreds of DA supporters to promote a youth subsidy she believes will mean more opportunities for jobless young South Africans. She told those who gathered to oppose her: "You are not on the side of the poor. The DA is on the side of the poor."

Her speech was drowned out by singing and shouting by hundreds of demonstrators who had come out in support of COSATU, the country's main union coalition. COSATU says the proposal to give businesses government subsidies to encourage them to hire young workers will lead to a lowering of wages for all workers.

After her opponents threw rocks at the truck from which she was speaking, Zille was bundled into a small car and driven away. Her supporters then started throwing rocks at the union protesters.

The DA believes the subsidy, proposed by the governing African National Congress, could create at least 423,000 jobs for young South Africans. South Africa's unemployment rate is high, with a quarter of the work force unemployed in the nation of 50 million people.

COSATU is a powerful ANC ally, but differs with the ANC on youth subsidies and could sway the party to drop the idea.

Tuesday's protest, though, was less about the merits of an economic proposal than about who has standing to speak.

The DA, which has its roots in a white liberal party that opposed apartheid, has struggled to build credibility among South Africa's impoverished black majority. Blacks and whites marched together in the DA's bright blue T-shirts Tuesday.

In a weekend statement, labor and student groups allied to the ANC had called the DA's plans "provocative and deceitful" and labeled the party a representative of "white monopoly capital and apartheid apologists."

The DA responded ahead of the march that labor leaders were threatening violence, and said "it is unacceptable in a constitutional democracy for union leaders to threaten those who challenge them on the basis of their policies and their actions."

On Tuesday, COSATU spokesman Patrick Craven condemned the violence and said COSATU supporters also were injured.

He denied the counter-protest was organized to silence the DA, saying workers gathered only to show they reject DA policies.

"It was certainly an attempt to have a show of strength. There was absolutely no intention to have violence," he said.

The DA had planned to end its protest at COSATU's headquarters, but the marchers turned away three blocks from their destination because of the violence. As the crowd made their way back into central Johannesburg, police sprayed stragglers with water from a truck.

Vusi Sefuba, a 26-year-old wearing a DA T-shirt, limped after the marchers as they retreated. He pulled up a pant leg to show a bruise on his left calf where he said he'd been hit by a rock.

"I don't see any progress in this country unless the DA takes over," he said.

Sefuba said he once supported the ANC, but has been working for the DA since an internal ANC power struggle led to a split in the governing party in 2008.

Mpopi Maubane, a 24-year-old student at a secretarial school, was split between the two sides Tuesday. She stood outside COSATU's headquarters with a white-on-red sign that read, "No to a 2-tier economy," an anti-youth subsidy slogan. But she said she knows the subsidy might help her get a job when she finishes school.

COSATU and the ANC have her loyalty, Maubane said, because they led the fight against apartheid.

"But we're also saying DA has a point," Maubane said.