The ANC's relationship with its union allies has been hit by a recent nationwide strike by some one million civil servants. But Zuma denied that the ANC's partnership with unions and the left was under threat, saying predictions of the imminent break-up were "a waste of time and ink".

He did, however, warn them that the ANC is the "leader of the alliance".

According to BBC, Zuma also took a stiff line on ANC members who publicly condemned the party, saying they would face discipline. "We have no choice but to reintroduce revolutionary discipline - junior structures must respect senior structures of the ANC," he said.

However, he said the party was more stable than seemed possible three years ago when it was divided between his supporters and those of his predecessor, Thabo Mbeki.

Zuma attacked what he called "worrying tendencies in the party, and individuals" he said "were seeking to put themselves forward for political gain."

Many believe this was directed at ANC youth wing leader Julius Malema, who has recently raised questions about President's Zuma's authority to lead and who is privately reluctant to back him for a second term. The speech was received with sporadic applause, most of which came when he spoke of party discipline.

The president steered clear of publicly pronouncing on Mr Malema's call for mines to be nationalised and the controversial proposed media tribunal, but correspondents say these will no doubt feature behind closed doors during the conference.