Johannesburg - The general secretary of the Congress of South African Trade Unions, Zwelinzima Vavi, says he is not going to resign.
He has been under intense pressure after the majority of unions voted to expel Numsa last year.
At one stage last year he was suspended for eight months.
Alleged impropriety
Meanwhile SAPA reported that Vavi said: "This [not resigning] is a deliberate act of defiance on my part, even if in the end it turns out to be symbolic," he told reporters at a briefing in Johannesburg.
"It sends a message to workers that we must refuse to hand the organisation over on a platter and must not only walk away when all alternatives to rescue it have been exhausted."
Cosatu belonged to all its members, and not any faction or clique, he said.
Vavi called a media conference to make "an important announcement," with many speculating that the beleaguered unionist would leave the federation.
On 5 March the CEC (central executive committee) announced that a forensic report into alleged impropriety in the sale of Cosatu's old head office and purchase of a new one implicated Vavi.
The report, by auditing firm Sizwe Ntsaluba Gobodo, which was handed to the CEC, showed that the auditors had not been able to meet Vavi despite their attempts to do so, the federation said then.
Mine company Aurora
There were allegations that Vavi's stepdaughter had been involved in one of the companies that worked on the head office transaction.
Vavi did not attend the CEC meeting on 2 March and instead attended a case in the North Gauteng High Court in Pretoria against mine company Aurora by its workers.
The embattled trade union federation has been dealing with its unions supporting either Vavi or Cosatu president Sdumo Dlamini.
Members of the National Union of Metalworkers filled the conference room and sang revolutionary songs at Cosatu headquarters.
Dressed in Numsa T-shirts, they sang songs supporting Vavi.