The National Union of Mineworkers (NUM) on Saturday lashed out at the National Union of Metalworkers South Africa (Numsa) for "attacking and making threats" against trade union federation Cosatu.
"They are suffering from what is called auto-immunity disorder," NUM general secretary Frans Baleni told reporters in Johannesburg.
"This is when a body immune system makes a mistake of attacking some cells of the same body. For them to go out and attack the federation, they are working for the enemy."
Baleni was briefing reporters on the outcome of the union's national executive committee (NEC) meeting held this week.
He accused Numsa and its allies of working for the benefit of capital.
"A weakened Cosatu will only benefit capital. Numsa has never rolled out a programme of action against employers but now it has a programme to fight against Cosatu," said Baleni.
He said the NEC resolved to respect the decisions taken by the Cosatu.
"No one should be above the federation, we must all be subjected to discipline.
"Regardless of the period we have served the federation, we should avoid the Morgan Tsvangirai option or the [Frederick] Chiluba option where trade unionist becomes a politician thinking they can take power," said Baleni.
The NEC urged Cosatu to be "decisive when dealing with errant behaviour within the union federation".
Numsa and Cosatu have been at loggerheads since Cosatu general secretary Zwelinzima Vavi was suspended for having an affair with a junior employee last year, among other allegations.
The metalworkers' union has also lashed out at Cosatu for refusing to hold a national special congress.
Earlier this month, Cosatu said it wanted Numsa to give reasons why it should not be suspended or expelled.
Numsa resolved at its congress in December not to support the ANC in the upcoming general elections.
The nine affiliates accused Cosatu of trying to destabilise Numsa, which is the trade union federation's biggest affiliate.
Cosatu has said Numsa, as a Cosatu affiliate, was bound by the trade union federation's policies and constitution. Cosatu is an alliance partner of the ANC. – Sapa