Numsa and its seven supporting unions have filed papers in the High Court in Johannesburg in a bid to get Cosatu to hold a special national congress.

"We have jointly filed papers with other affiliates to demand convening of the special national congress," Numsa spokesperson Castro Ngobese said on Wednesday.

The National Union of Metalworkers of South Africa (Numsa) was expelled from the Congress of South African Trade Unions (Cosatu) earlier this month.

A special central executive committee (CEC) meeting expelled Numsa with a vote of 33 for and 24 against after the trade union federation charged the union with violating its constitution.

Cosatu said Numsa could appeal its expulsion at the federation's next national congress, which is expected to be held in September next year.

Ngobese on Wednesday said Numsa's call for a special national congress was never about its expulsion but about dealing with the "paralysis in Cosatu".

Cosatu has been wracked by internal divisions since its general secretary Zwelinzima Vavi was suspended last year for having an affair with a junior employee, among other things.

Numsa, a strong ally of Vavi's, took Cosatu to court over his suspension. Earlier this year the suspension was overturned and Vavi returned to work.

Numsa and seven other Cosatu affiliates wanted a special national congress so that new leadership could be elected.

Following Numsa's expulsion, Vavi wrote to affiliates saying he could not support Numsa's expulsion.

The Food and Allied Workers Union (Fawu) confirmed that the seven unions, who were against Numsa's expulsion were joining the metalworkers union in its court bid.

The unions were the SA Commercial Clothing and Allied Workers Union (Saccawu), the Communication Workers Union (CWU), Fawu, the South African State and Allied Workers Union (Sasawu), the Public and Allied Workers Union of SA (Pawusa), the Democratic Nurses Organisation of South Africa (Denosa), and the South African Football Players Union (Safpu).

Following Numsa's expulsion the seven unions announced that they were suspending their participation in Cosatu's CEC – the trade union federation's highest decision making body – until it had received mandates from its members on a way forward.

On Wednesday, a sitting of the CEC went ahead without the unions' participation.

The meeting was a continuation from the special CEC held on November, when Numsa was expelled.

The agenda for the last meeting included an update on the disciplinary process against Vavi, an update on litigation against Cosatu, president Sidumo Dlamini's report on the request for the special national congress, and the signing off of the draft secretariat report.

These items had been put on hold since April when the African National Congress task team intervened to help Cosatu with its internal problems.

According to the Sowetan newspaper, Vavi could face fresh charges for publicly denouncing Numsa's expulsion.