Pretoria - Granting approval for the contentious Walmart Massmart Holdings [JSE:MSM] merger was a serious error by the Competition Commission, Cosatu general secretary Zwelinzima Vavi said on Wednesday.He told an SA Commercial, Catering and Allied Workers' Union (Saccawu) conference in Centurion that the deal would have detrimental effects on South Africa's economy."The Competition Tribunal did not consider the broader interests of the South African economy and its people when it approved that merger," said Vavi."It should have looked at the rate of unemployment in our country which today stands at 36.6%. It should have looked at our poverty and inequalities."Vavi said the entrance of Walmart into the South African market would threaten even the existence of established retail shops like Shoprite Holdings [JSE:SHP] and Pick n Pay Stores [JSE:PIK]."We warned that this thing was going to be a giant. It's going to be swallowing everything that moves in the economy," said Vavi."This is the beginning of the race to the bottom," he said.Vavi said jobs would be lost as local retailers tried to align their operations with those of the world's largest retailer.He commended the government for its support during the failed attempt to block the merger."They stood next to us and made the same arguments we were making up to the last moment. They were with us. They lost with us," he said.*Follow Fin24 on Facebook, Twitter and Google+.