Democratic Alliance leader Helen Zille speaks during their youth wage subsidy march in Johannesburg, Tuesday, 15 May 2012.Picture: Werner Beukes/SAPA

DA leader Helen Zille was interrupted while speaking at a protest against Cosatu over the youth wage subsidy when violence erupted in Johannesburg on Tuesday.

Tension was in the air as she took the microphone in the city centre.

The louder she spoke, the louder chants from Congress of SA Trade Union (Cosatu) supporters at the event became. At some point, they hurled chunks of cement and rocks at Democratic Alliance supporters.

The police formed a human chain by linking hands in front of Cosatu supporters to stop them from getting to DA marchers.

It was a battle of the blues versus the reds as the number of Cosatu supporters increased.

Zille was forced to abandon her speech and the DA truck retreated.

Before the retreat, addressing the crowd in Xhosa, Zille said the march was in solidarity with unemployed South Africans.

“The millions of ordinary men and women who are looking for a fair chance to build a better life for themselves and their families,” she said.

“Today we protest against the organisation that is keeping them unemployed, that is keeping them locked out of the economy and denying them the dream of a better future. We all want to live lives that contribute to society.”

DA parliamentary leader Lindiwe Mazibuko and DA youth leader Makashule Gana could not deliver their speeches as the DA members retreated from violence by Cosatu members.

Earlier, Mazibuko told the crowd they were on the same side, fighting for economic freedom.

“I felt sad that South Africans, who fought for tolerance and freedom, couldn't exercise those rights today,” she said.

At least two people were injured when rocks were thrown, and police fired teargas.

Paramedics could not make their way through the crowd so the injured were taken out on the DA's truck.

However, Cosatu supporters chased the truck down two blocks before police managed to contain the situation.

The streets were strewn with rocks and litter and riot police fired a water cannon at the rowdy Cosatu crowd.

On social media site Twitter, the DA march, Cosatu, Helen Zille, youth wage subsidy, Braamfontein, Irwin Jim and Democratic Alliance were trending on Tuesday afternoon in South Africa.

Journalist, Nickolaus Bauer tweeted: “Just been hit with a rock in the #DAmarch crossfire. The price you pay for trying to report the truth.”

Bauer also added a picture where blood can be seen on his face.

National DA spokesman Mmusi Maimane said the party noted that the Cosatu leadership had not condemned the violence by members.

“We will be laying criminal charges against Cosatu’s leadership for intimidation, inciting violence, and holding an illegal gathering,” he said.

DA protesters taking part in the march earlier took off their blue T-shirts in fear of being targeted by Congress of SA Trade Unions supporters.

Marching down Jorissen Street in Braamfontein, they were met head-on by a group of people in red T-shirts. Cosatu supporters intimidated the DA crowd and stopped them from proceeding to Cosatu House.

Earlier, there was a loud bang, believed to be the police firing teargas at Cosatu supporters.

In a statement, DA spokeswoman Kate Lorimer said not enough police and metro police officers had been at the march.

“The legal DA march has been met by an illegal gathering of violent (National Union of Metalworkers of SA) and Cosatu members who are throwing bricks and stones at peaceful DA marchers,” Lorimer said.

“It seems though as if the cops were unprepared and it was only after the stone throwing that the (SA Police Service) finally sent in a police vehicle to block the Cosatu attack.”

In her speech, Zille said the youth wage subsidy would create 400,000 first-time job opportunities.

She said Finance Minister Pravin Gordhan had set aside R5 billion for the first phase of the project.

“Cosatu has been using its political clout in the ANC government to block the implementation of the youth wage subsidy for two years now,” she said.

“Cosatu's leadership says that it knows the plight of the unemployed, yet it is happy to undermine the futures and aspirations of those same people. By opposing the subsidy, Cosatu is entrenching inter-generational poverty for at least another generation.”

Cosatu general secretary Zwelinzima Vavi said a youth wage subsidy would use workers' tax money to further enrich company bosses and had to be opposed.

“What will happen is when workers get old, bosses will throw them into the street,” Vavi said in Johannesburg.

He said youth receiving the subsidy would also not receive a full wage.

“We demand equal pay for work of equal value.”

Vavi was addressing a crowd outside Cosatu House in Braamfontein.

In a media statement, Mazibuko said Cosatu's hypocrisy was hurting South Africa.

“Mr Vavi loves to talk about Cosatu as a champion of the poor; an organisation which is anti-corruption and pro-accountability,” she said.

“The truth is that Mr Vavi doesn't really care about the needs of South African people. Making an empty spectacle is how he manages to have his cake and eat it. And what a cake it is. Look at these massive R50 million headquarters.”

Several hundred DA supporters started their march at Beyers Naude Square in the city centre to protest against the Cosatu's opposition of the youth wage subsidy.

They moved along President, Rissik, Jeppe, Sauer, Burger, Jorissen, Melle, and Simmonds streets. - Sapa