COSATU general secretary Zwelinzima Vavi's speech brought central Johannesburg to a standstill as thousands of public servants filled the streets in solidarity against government's wage offer.

Usually busy roads were closed for about five hours as union members marched along them, singing struggle songs and handing memorandums to Gauteng Premier Nomvula Mokonyane and several MECs.

As the strike entered its 10th day yesterday, Vavi threatened the state with a massive sympathy strike next Thursday.

"We will not allow that you go back to your work places without a victory in your hands," he said.

Listing Cosatu affiliates, Vavi said: "All the unions of Cosatu, they will issue notices to their employers to say they will be joining the public servants' strike".

"In terms of [the] Labour Relations Act, unions must [give seven days' notice of their intention to strike]. So we say to the government today, you have only less than seven days. In seven days, the whole of this economy will stand still."

Vavi challenged the government, saying: "Better phone us now, send an SMS, our phones are open. And please don't call us for 7% ... let's talk and let's talk serious money."

Striking workers, who are demanding an 8.6% pay rise, came out in full song, insulting Public Service and Administration Minister Richard Baloyi.

They displayed placards bearing messages such as: "Comrades, let's stick together like buttocks, if we split, s*** [7%] will come out". Another placard read: "If you want to pay peanuts, employ monkeys."

Other posters insulted President Jacob Zuma and members of his Cabinet, with messages such as: "Zuma, your wives deplete state funds" and "Angie [Motshekga], don't talk rubbish, take that R700 and buy yourself a nice set of teeth".

Vavi lashed out at police officers affiliated to Popcru who have not joined the strike, criticising them for their "brutality" at the Helen Joseph Hospital when they fired rubber bullets and arrested five health workers.

"To the police, we want to say this is our battle, but it is your battle too.

"When Sepp Blatter was here with his people, you were trained to use a civilised way of crowd control. Why rubber bullets now?

"Why are you shooting at your own colleagues? Why are you dragging your own mothers in the streets as if they are dogs? Where is solidarity?"

Vavi said Cosatu was continuing to negotiate with the government .