One of the ANC's biggest voting regions in the Eastern Cape has thrown down the gauntlet by electing a leader who is anti- Jacob Zuma.

The election of Sandile Sello as chairman of the Alfred Nzo region could signal the beginning of a fight to oust Zuma in Mangaung later this year.

The region, which includes areas such as Bizana, Matatiele and Mzimvubu, was the first in the province to hold its elective conference ahead of the May deadline to elect leaders.

The SACP's chairman for the region, Phikolomzi Siramza, stood for the ANC post but lost to Sello.

Siramza's supporters are challenging the outcome of the vote and have lodged a dispute with the ANC provincial working committee.

The party's Eastern Cape secretary, Oscar Mabuyane, confirmed delegates from Alfred Nzo had visited the provincial head office on Monday.

"But [the working committee] agreed that indeed the conference took place, there is an outcome [and] there is leadership that we recognise in Alfred Nzo."

The drama started on Saturday, when delegates at the elective conference questioned a credentials report presented by the previous regional secretary, General Moso.

Delegates started singing songs in support of Zuma, while others sang different songs. The police were called in when the rival groups threw chairs at each other.

The party's provincial deputy secretary, Helen August, ruled that Moso's credentials report be adopted.

Both groups then nominated candidates for the top five positions. All leagues supported the Sello line-up, while the SACP supported Siramza's.

The party wants both Zuma and ANC general secretary Gwede Mantashe to retain their positions, Sello's supporters want change.

Mabuyane said the province would investigate claims that branch general meetings were not conducted properly before the elective conference.

He said Buffalo City was scheduled to hold its elective conference in two weeks' time, followed by Amathole and OR Tambo at the end of March. The rest would hold theirs in May.