Some deals giving black South Africans stakes in the financial sector are breaking the rules, according to trade union group Cosatu.
Not everyone has benefited from black economic empowerment
Cosatu warned of "big empowerment share deals taking priority over truly broad-based black economic empowerment".
The accusation comes after Standard Bank agreed to sell a stake to a group led by ex-ANC chief Cyril Ramaphosa and businessman Saki Macozoma.
Economic empowerment is a key policy of the ANC government.
But it has been heavily criticised for not distributing wealth to a greater number of people.
"There is a clear attempt to downplay genuine broad-based economic empowerment and access by millions of our people to finance," Cosatu and its South African Communist Party partner said in a statement.
The South African bank Absa also agreed to sell a 10% stake to a consortium headed by a former freedom fighter Tokyo Sexwale, who was imprisoned with Nelson Mandela.
Last October, the financial sector agreed on a charter which set a 10-year goal to give South Africans a greater share of banks, insurers and investment groups.
"These agreements outlined a package of changes to better the majority of South Africans, not just an elite minority," Cosatu said.
The Banking Council of South Africa's Caz Coovadia noted that the transfer of control to black South Africans is just part of the charter, with four-fifths of the weighting on the empowerment scorecard focusing on "broad-based empowerment".