No investigation is being conducted into corruption allegations against Cosatu general secretary Zwelinzima Vavi, the trade union federation said on Monday.
"There is a discussion on certain issues... in a private process," spokesman Patrick Craven said.
"It is not an investigation and it is not an investigation into a certain individual."
The Sunday Times reported that Congress of SA Trade Unions affiliates would begin testifying this week against Vavi. According to the report, the decision to start the probe was taken at a meeting of Cosatu-affiliated union presidents and secretaries in Johannesburg last Monday.
"From April 19, affiliates will be making submissions to the commission. The commission will investigate all the allegations against Vavi," a Cosatu leader told the newspaper, speaking on condition of anonymity.
Craven dismissed the report as being part of a concerted campaign by someone to damage the trade union federation.
"We condemn it utterly, this use of anonymity to conduct a campaign against Cosatu."
On Sunday, Vavi took to social networking site Twitter to dispel the rumours.
"There is no probe the only meeting tomorrow [Monday] is for campaigns to implement bargaining conference declaration," Vavi tweeted.