The Congress of South African Trade Unions (Cosatu) has opted to keep mum on reports that President Jacob Zuma fathered a child with the daughter of soccer boss, Irvin Khoza.

The trade union federation and African National Congress (ANC) ally on Wednesday said that it had taken note of the reports but would not comment or "pass judgment" until Zuma himself confirmed or denied the allegations.

Cosatu had, however, reaffirmed its commitment to the fight against HIV/Aids.

Opposition parties condemned Zuma's conduct, with the Democratic Alliance charging that it had damaged the fight against the pandemic.

Cosatu spokesperson Patrick Craven said that the only way to defeat HIV/Aids was to repeat the message of abstinence, being faithful to one partner or using condoms, to the youth, the workers and all South African citizens.

"No matter what the conclusions of the current discussion, the federation calls on all South Africans, in particular the youth and women, who statistically are more ravaged by the scourge of HIV and Aids, to recommit themselves to the basic tenets of our common campaign," he said.

The Sunday Times reported that Zuma fathered a child with Sonono Khoza, the daughter of soccer tycoon and World Cup local organising committee chairman Khoza.

The child was reportedly born on October 8, three months before Zuma - a polygamist - married for a fifth time. The baby girl was said to be the President's twentieth child.

According to the Sunday Times, a delegation acting on Zuma's behalf, visited the Khoza family in December to discuss the Zulu customary damages, inhlawulo, that are due when a child is born out of wedlock.

The Times reported on Wednesday that it had evidence suggesting that Zuma and Khoza were already married according to customary law.

The ANC had stuck by the President amidst the furore, saying there was nothing wrong with what he had done.