Numsa general secretary Irvin Jim wanted his Congress of South African Trade Unions (Cosatu) counterpart Zwelinzima Vavi to be elected as African National Congress (ANC) deputy president in 2012, South African Communist Party (SACP) general secretary Blade Nzimande said on Thursday.

"I don't want to be misread. I don't know whether comrade Vavi was consulted or not. It is not a criticism of comrade Vavi," he told delegates at the Young Communist League of South Africa's national congress in Cape Town.

He said he was merely telling the truth and could guess what ANC president Jacob Zuma said when Jim apparently approached him with the request.

"I can guess. He said if anyone has to be deputy president, they must first join a branch of the ANC and rise through the ranks."

Nzimande wondered where the National Union of Metalworkers of South Africa (Numsa) had got its mandate from.

"That is the source of the problem with Numsa. We said to the metal workers, ask. Now we are being blamed for causing problems in Numsa and Cosatu. We can't manufacture a deputy president."

Jim told reporters in Johannesburg on Thursday that Numsa was challenging its expulsion from the Cosatu in court.

Numsa was expelled from Cosatu last month. According to Cosatu's constitution, Numsa could appeal its expulsion at the next national congress which was supposed to be held in September next year.

However, Cosatu president Sidumo Dlamini said earlier this week that Cosatu would now hold a special national congress in July.

Numsa was a strong supporter of Vavi when he was suspended last year for having an affair with a junior Cosatu employee.

The metalworkers union took Cosatu to court to challenge Vavi's suspension, where it was successful.

The High Court in Johannesburg overturned Vavi's suspension and he returned to work earlier this year.

An ANC task team has stepped in to help the embattled Cosatu deal with internal friction, the expulsion of Numsa and with disciplinary proceedings against Vavi.

However on Thursday, Jim criticised Zuma's government.

"The ANC/SACP government is now more degenerate and dangerous to the working class than even the government of Thabo Mbeki was," he told reporters in Boksburg on Johannesburg's East Rand.

Nzimande was warmly received by delegates at the University of Western Cape on Thursday, and was applauded and cheered when he listed the achievements of the ANC since the end of apartheid.

He encouraged members of the Young Communist League of South Africa to continue building a progressive youth movement characterised by disciplined militancy.