Although a decision to leave Cosatu has not been made, it is a point of discussion within the trade union federation, its general secretary Irvin Jim said on Tuesday.
"It's one of the options that's being debated," he told reporters in Johannesburg.
"I guess if you can get married, you can get divorced."
A discussion document about the National Union of Metalworkers of South Africa's (Numsa's) decision to leave Cosatu was leaked to a Sunday newspaper.
Jim said the document would be discussed at Numsa's special conference next month.
"There is no need for speculation. There is no decision that Numsa is moving away from Cosatu. It's one of the options that's being debated."
Numsa treated unfairly
Last week, Numsa claimed it was being treated unfairly by Cosatu after calling for a special national congress.
Nine of Cosatu's 19 affiliates called for a special national congress after Cosatu general secretary Zwelinzima Vavi was placed on special leave in August for having an affair with a junior employee.
In September, Cosatu president Sdumo Dlamini said Vavi did not feature in the unions' reasons for calling the special congress.
Numsa lodged an application in the high court in Johannesburg challenging Vavi's suspension.
Cosatu, after its three-day central executive committee meeting last week, asked Numsa to withdraw its court challenge. – Sapa