Deputy President Jacob Zuma called on delegates at the Congress of SA Trade Unions national congress on Tuesday to defend the country and freedom against what he called counter-revolutionaries.

"It is our duty as the tripartite alliance to deepen democracy in South Africa and defend the country against fly by night counter-revolutionaries because no one will do that on our behalf," said Zuma in his unscheduled address at the congress in Midrand.

"As the congress deliberate on issues, you must ask: how should we move forward? How do we fight against corruption, misuse of power and counter-revolutionaries?"

The alliance comprises the African National Congress, the SA Communist Party and Cosatu.

Zuma, who arrived at the congress an hour after President Thabo Mbeki, said the alliance should work on creating more conducive conditions for workers and all of its citizens.

"The ANC, to which the majority of us here are members, has an objective in the alliance to fight and protect the freedom all of us attained."

He said the SACP was equally important to the alliance as other members.

"They (SACP) have their own destination. When the ANC arrived at its destination, which was to democratise the country for the betterment of all its citizens, the SACP said it will stop its journey once socialism has been achieved," Zuma said.

"This does not mean, as our distracters say, the alliance is in conflict with itself. This only signifies the variety of ideologies which form up the tripartite alliance."

Zuma received a standing ovation after his off the cuff address and adorned a blanket that had the labour federation's logo and trademark.

Earlier on Tuesday, proceedings at the congress were briefly interrupted as Cosatu members sang liberation songs to welcome Zuma's arrival at the meeting.

The ululating and cheering members chanted slogans supporting Zuma while some walked up to the podium to greet the deputy president.

Once again delegates sang a song denouncing National Prosecution Authority head Bulelani Ngcuka.

"Ngcuka uvulela impi, ubiza umlo," (Ngcuka you are calling for war), sang the group outside the entrance of the congress venue.

"Wena ulawula ama Scorpions sitshele ukuthi uZuma wethu wenzeni?" (Head of the Scorpions tell us what our leader has done?)

Ngcuka and Zuma have been at loggerheads ever since the elite detective unit announced it was investigating Zuma on bribery allegations related to the controversial arms deal.

With acknowledgements to Anele ka Nene, Sapa and Independent Online.