If corruption and factionalism are not resolved they could tear Cosatu and its alliance partners apart, the trade union federation's general secretary Zwelinzima Vavi said on Monday.
"Unless corruption, incompetence and wastage is stamped out, it will continue to sabotage our struggles for a better life for workers and the poor," he said at Cosatu's KwaZulu-Natal conference in Pietermaritzburg.
"We desperately need a mindset change throughout society, but particularly in our revolutionary movement."
Some 1388 delegates from affiliated unions, including the National Union of Metalworkers of SA and the SA Democratic Teachers' Union, were attending the three-day event which started on Sunday. They would elect new provincial leaders.
Vavi said the emergence of factions was robbing the labour federation and its alliance partners in the African National Congress and SA Communist Party of good leaders.
"The main reason why leadership has been weakened is that almost every leader today in the movement is a product of slate politics, divisions and factionalism."
Slates are lists of candidates for top leadership positions drawn up by different factions.
Vavi urged union members not to turn a blind eye to corruption.
"We must keep repeating, repeating our call for heads to roll where there is clear evidence of incompetence and corruption. We must also keep pressure on public representatives who face charges of serious offences to voluntarily step down from office until their case has come to court, and if they refuse, to [be] suspended."
He conceded corruption was not limited to the ruling party, but had found its way into trade unions.
"Our provincial and national congresses must ask soul-searching questions about whether our leaders or officials are accepting money from employers in return for favours or looting provident funds."
He cited the widening gap between rich and poor, the rise in poverty and income inequality as some of the problems facing the country, but welcomed the ANC's acknowledging there were problems.
"Finally we have a government and ruling party who realises that we are facing a national crisis, a welcome move from the denialism of a few years ago," he said in an apparent reference to the Thabo Mbeki-led government.
He told delegates Cosatu would continue to fight for the scrapping of labour brokers, which he said equated to human trafficking.