Some waved their hands in three-fingered salutes, indicating they wanted a third term for Mbeki, while Zuma supporters signalled their desire for change by rolling one hand over another, as if to call for a substitute during a football game.
Fikile Mbalula, president of the ANC Youth League, which has been a strong Zuma supporter, called for delegates to be disciplined.
Confusion and procedural wrangling have badly delayed the work of the five-day conference, which should have quickly resolved the leadership issue and moved onto policy discussions.Counting row
Jeff Radebe, the transport minister, had told reporters that the delegates were split on whether to count the leadership ballots manually or electronically.
Zuma's supporters had demanded that the votes be counted by hand, saying that the process must be transparent and insinuating that the Mbeki era has not been transparent.
"There is absolutely no clarity as to when there will be a result, given the fact that there is not yet even agreement about the procedures that will lead to that result."
If Zuma wins, he will almost certainly also succeed Mbeki as the country's president in 2009 due to the party's electoral dominance.
Mbeki is barred by the country's constitution from seeking a third term as the country's president. But if he were to remain the ANC leader, he would influence the party's choice for the next president.
Zuma took the lead over Mbeki in branch elections for the ANC presidency, winning the support of five out of the nine ANC provincial branches as well as the backing of the women's league and youth league in a first round of voting before the conference.
The infighting caused deep concern in an organisation that prided itself as presenting a united front during the struggle against apartheid and has ruled virtually unopposed since 1994.
|Mbeki is hoping to secure a third term |
as president of the ANC [AFP]
"The organisation is going through deep strain," Smuts Ngonyama, ANC spokesman, said.
Nelson Mandela, the 89-year-old former president, who has retired from politics but who is still seen as a unifying figure in the country, also expressed his concern at the divisions in the party.
"It saddens us to see and hear of the nature of the differences currently in the organisation," he said in a message to the delegates distributed by the South Africa Broadcasting Corporation.
"Whatever decision you are to make at this conference, including decisions about leadership positions in the organisation, let the noble history of the ANC guide you."
Zuma is a controversial figure. He was acquitted of rape last year but is still under investigation for corruption.