Johannesburg - If the demands of the four striking freight unions were not met at a meeting with employers on Tuesday, the nationwide strike would continue, the Professional Transport Workers Union (PTWU) said.
"If the employer refuses it, it will mean that we will continue with the national strike," PTWU spokesperson Reckson Baloyi said.
This came after trouble erupted during protest action on Monday.
Four freight workers were injured after police fired rubber bullets in a protest that turned violent in the Johannesburg city centre.
It started at midday when the protesters, including those from the SA Transport and Allied Workers Union (Satawu), smashed the windows of 10 trucks, pulled drivers out of their vehicles and forced them to join the march.
"The protest turned violent on Rissik street at about 12:20," said metro police spokesperson Chief Superintendent Wayne Minnaar.
"The protesters smashed the windscreens of trucks. The situation was tense.
"Later in the afternoon the situation had calmed. The metro police and members of the SA Police Service were keeping a close watch on the protesters..."
Baloyi said the unions would meet with the Road Freight Employers Association (RFEA) in Boksburg at 10:00 to negotiate their demands.
"We are going to negotiate in good faith to resolve the strike," Baloyi said.
The unions involved in the wage dispute are the PTWU, Satawu, the Motor Transport Workers Union (MTWU) and the Transport and Allied Workers Union of SA (Tawusa).
The workers are demanding an increase of 20% over the next two years and the banning of labour brokers.
The RFEA was offering an increase of 7.5% across the board for 2011 and a further 7.5% increase for 2012.
The wage talks between the unions and RFEA deadlocked in December.
Truck drivers started a go-slow on Sunday.
Baloyi said cash-in-transit drivers should receive an increase of 17% and truck drivers an increase of 10% - and only then would they "settle as unions".