Tens of thousands of protesters marched through South African cities on Wednesday in a protest by the powerful Cosatu labour body, the latest sign of tensions within the ANC-led government. The protest\'s official rallying cry is to demand that government scrap plans for tolls on major roads around Johannesburg and rein in the practice of labour brokers who offer workers short-term contracts at lower pay. But the marches were another show of discontent with the African National Congress-led government, which has ruled since Nelson Mandela became the first black president in 1994. \"We have come here to fire the first warning shot. And in our chamber, there is still a lot of bullets,\" Cosatu chief Zwelinzima Vavi told a cheering Johannesburg crowd that police estimated at 45,000. Vavi drew a line in the sand on tolling set to start at the end of next month, threatening to shut down the highways of South Africa\'s economic heartland. \"If they say they will introduce this, we will take everybody we see here and even more and put them in the highways of Johannesburg,\" he said. \"We will make this system unworkable.\" \"That is a form of privatisation of the roads. Instead of the (city) council providing us with the services, the basic services, such as roads and public health assistance, we must now pay for everything,\" he said. \"The government loses 30 billion rand ($3.9 billion), that is a financial year, to graft or fraud,\" he said, citing a report last year by official investigators. The embattled leader of the ANC Youth League, Julius Malema, stood behind Vavi as he spoke -- just a week after the party moved to expel him for provoking divisions within its ranks. Malema, who has vowed to appeal his expulsion, had become a leading voice opposing Zuma\'s re-election as ANC chief at the party\'s elective conference in December. And while the protest avoided overtly political tones, Cosatu\'s underlying message was clear: Zuma will still have to earn its support. Cosatu organised marches in 32 towns and cities, with Johannesburg, Cape Town and Durban posting the biggest turnouts. Plans for toll roads have provoked widespread anger across Gauteng, the tiny province that includes Johannesburg and the capital Pretoria. \"We pay for petrol, we pay for our cars and maintenance, now this,\" said Johannesburg marcher Fulelo Nokwe, who commutes across the length of the sprawling city every day. \"This is our land, why pay for it? We are already paying hefty taxes,\" he added. Many poor South Africans will not be affected, because mini-bus taxis used by most commuters are exempt from the tolls. The finance ministry says tolls are an essential part of financing the 33 billion rand loans used to upgrade the highways ahead of the 2010 football World Cup. The government has already dropped the proposed toll rates by 40 percent, and agreed to a cap of 550 rands ($72) a month in toll payments for motorists. On the streets, the issue of labour brokers was clearly a major concern. Many businesses rely on labour brokers and a study last month found that 30 percent of the national workforce was employed on temporary contracts, a system that Cosatu says is open to abuse. It wants temporary contracts limited to six months and paid at rates equivalent to full-time jobs. One protester said he had worked for three years for a construction company on temporary contracts. \"They are parasites, they exploit people. How can I be a temp for such a long time?\" he said, identifying himself only as Travis. \"These people are colluding with big firms to exploit us. We want full-time employment with security and benefits,\" he said.