AFRICAN Rainbow Minerals (ARM), owned by businessman Patrice Motsepe, is the largest private donor to Cosatu, having contributed R1.75-million to the trade union federation over the past three years.
This does not include ARM's donation to this year's congress, where Motsepe was again the biggest donor.
The size of this year's donation has not yet been disclosed.
Motsepe funded Cosatu's previous conference in 2009 to the tune of R1-million.
In the same year he also donated R1.75-million to Cosatu's Violet Seboni Trust, which supports the dependants of deceased national office bearers.
The details of the donations made by ARM, as well as several other companies, are contained in Cosatu's treasurer's report, adopted by the congress yesterday.
They come in the context of the emergence of accusations by some workers that Cosatu unions are too close to business.
Other large corporate donors were Investec, which funded last year's central committee meeting with a R1-million donation; Standard Bank, which contributed R850000 to the 2009 congress; and Sanlam, which donated R50000 and R100000 for the 2009 congress and to the Violet Seboni Trust respectively.
Cosatu's financial statements show that in December last year the federation had a surplus of just over R1-million.
Its main source of income is from affiliate fees with each of Cosatu's 2.2 million members paying a monthly fee of R2.67 last year.
Income from affiliates was R65-million last year.
Cosatu affiliates also contribute to a political fund reserve, which is used to fund campaign activities and political allies.
Over the past three years, Cosatu has donated R3.7-million to the South African Communist Party (SACP).
This is despite the fact, revealed in Cosatu's organisational report, that only 6% of Cosatu members are members of the SACP.
Cosatu also provided just over R900000 to the ANC's election campaign in 2009.