Solidarity has asked LNM Holdings owner Lakshmi Mittal to show his good will towards both Iscor staff and South Africa by placing a one-year moratorium on retrenchments, said spokesman Dirk Hermann in a statement.
LNM vice chairman Aditya Mittal wasn't available for comment on Solidarity's request. LNM is the world's second largest steel group and has a 49.9% stake in Iscor.
South Africa's Competition Tribunal held hearings on Monday and Tuesday regarding LNM's move to increase its stake in Iscor above 50%.
Solidarity said that according to Iscor's latest annual repor LNM paid about R2.8bn for its shares and the market value of those shares now stands at around R7.8bn, implying a gain of R5bn.
"Iscor's workers suffer from retrenchment fatigue. Mittal should understand that workers feel rebellious when they see that the major shareholder shows excessive capital growth, while they labour under the sword of more dismissals," Hermann said.
The union stated that during the past ten years around 30 000 Iscor workers have lost their jobs.
"We resentfully read of Mittal's extravagant lifestyle. He bought the world's most expensive house, at a cost of almost one billion rand, and paid R400m for his daughter's wedding," Hermann added.
"Workers in South Africa are sponsoring this luxurious lifestyle," Hermann said.