Thousands of workers gathered in Newtown, central Johannesburg ahead of a nationwide strike called by the South African Federation of Trade Unions (Saftu).

The federation's more than 20 unions, including the National Union of Metalworkers of South Africa (Numsa) and Tirisano Transport Workers Union (Taswu), are taking part in the march to put pressure on the government not to implement a contentious R20 per hour national minimum wage bill.

They say the amount is too low, and have also spoken out against other proposed amendments to labour laws.

Rival federation the Congress of South African Trade Unions (Cosatu), which is in a governing alliance with the African National Congress, has distanced itself from the strike, saying that it supports the minimum wage tabled.

“To hell with R11, R14, R18 and R20 per hour. We demand a R12,500 living wage,” read some of the placards held by protesters on Wednesday.

Some of the workers, wearing T-shirts bearing the logos of their unions, sang songs slamming President Cyril Ramaphosa.

The start of the march was slightly delayed as some workers were still making their way to the venue. Some were believed to have been affected by an going separate strike for higher wages in the transport sector which began on April 18.

Numsa national youth coordinator Zwelohlange Ndiki told marchers not to despair despite the lack of support from Cosatu.

"We must tell Cosatu that we no longer actually want to be part and parcel of them," he told the cheering crowd.

"They must mind their business, whatever we do has nothing to do with Sdumo Dlamini, Bheki Tshalintshali, they must shut up." Ndiki said, singling out some Cosatu leaders by name.

Saftu earlier this week announced it would embark on a general strike over what it terms "the biggest attacks on working-class people, trade unions and the poor" since the end of apartheid.