The Western Cape branch of the Congress of South African Trade Unions (Cosatu) called on the government to block the sale of the “key strategic national company”.
“We will oppose the setting up of any Walmart stores in the Western Cape. Walmart is notoriously anti union and anti workers rights, and an affront to workers rights wherever they operate around the world,” a spokesperson for Cosatu said.
Wal-Mart tried to stop any government probe in its tracks by vowing to respect labour legislation and insisting it would not change workers’ terms and conditions.
Doug McMillon, president and chief executive of Wal-Mart International, said: “We respect and honor pre-existing union relationships and are committed to abiding by South African labor laws.”
Unions wield huge power in South Africa, having funded and organised Jacob Zuma’s successful presidential campaign in 2009.
However, Zuma has tried to distance himself from the unions since taking power, insisting market reforms are necessary to boost Africa’s largest economy, which is growing at a slower pace than other emerging countries.
Wal-Mart has made a non-binding proposal of 148 rand (£13) per Massmart share, valuing it at around 30bn rand (£2.7bn), a premium of nearly 10 per cent over its pre-offer closing price of 134.75 rand.
Massmart has granted the US firm an exclusivity period but there is no certainty of a formal offer. Buying Massmart would give Wal-Mart a considerable network in South Africa and a foothold in 13 other countries in sub-Saharan Africa.