JOHANNESBURG (Reuters) - South Africa's largest trade union and ally to the ruling African National Congress (ANC) Cosatu said on Tuesday that President Jacob Zuma must step down after his change of finance ministers triggered a credit rating downgrade to "junk".


The trade union said it no longer believed in Zuma's ability to lead the party and the country, and that it would call for the alliance with the ANC to restructured.


(Reporting by Nqobile Dludla and Joe Brock; Writing by Mfuneko Toyana; Editing by James Macharia)