Johannesburg -There may be disruptions to milk supplies if the current strike by Clover workers is protracted.
The General Industries Workers Union of South Africa (GIWUSA) said more than 2,000 workers have downed tools.
It expects members of the Food and Allied Workers Union (FAWU) to support the strike at factory and plants on Tuesday.
Workers have rejected a final wage offer of a 4.5% backdated to July.
Clover said it has put contingencies in place to limit the impact of the strike but warns supplies may be disrupted.