POLOKWANE, South Africa - The top prosecutor in South Africa signaled yesterday that criminal charges would soon be filed against the newly elected leader of the ruling party, Jacob Zuma, complicating a comeback that has taken Zuma from political outcast to presidential favorite.

The news came the same day Zuma broke his weeklong public silence to call on members of the African National Congress to heal rifts left by the most fractious power struggle in the party's modern history.

He won that battle Tuesday, besting incumbent Thabo Mbeki to take control of the party. But Zuma now faces the likelihood of a prosecution that, if successful, would make him ineligible to become the nation's president and possibly land him in jail.

Prosecutors for several years have investigated Zuma's role in a multibillion-dollar arms deal, including allegations that he took bribes to block investigations.

Yesterday, Mokotedi Mpshe, acting national director of public prosecutions, told a radio station in Johannesburg that a final decision on whether to file charges was imminent.

"The investigation, with the evidence we have now, points to a case that can be taken to court," Mpshe told Radio 702, according to the South African Press Association.

The looming charges complicate an already tense political situation in South Africa. Thirteen years of stability anchored by the party that ended apartheid are now clouded by the rivalry between Zuma, leader of the ANC, and Mbeki, leader of the national government.

Mbeki fired Zuma as deputy president of the nation in 2005 over the same corruption allegations that prosecutors now are investigating.

News reports here say Zuma may force Mbeki to give up power before the next general election, now scheduled for 2009.

Meanwhile, Zuma may have to spend much of the next several months in court. He already has won acquittal on unrelated rape charges and dismissal of an initial round of corruption charges.

Yesterday, he repeatedly declined to say what he would do if he was charged, telling journalists, "I will cross that bridge when I get there."

In addition to making Zuma ineligible to become president of South Africa, a conviction likely would prompt calls for him to abandon his party post. Should he do so, the party's newly elected deputy president, Kgalema Motlanthe, would be expected to take control and become a candidate for national president.

Debate over the possible fates of Zuma, Mbeki and Motlanthe marred a tightly scripted effort yesterday to reunify their factions at the end of the ANC's five-day national conference.

Zuma's 40-minute speech to delegates included assurances of cooperation with Mbeki, who watched from the front row of the audience. Zuma called Mbeki his brother and "indeed my leader."

Zuma later delivered much the same message in an 80-minute news conference in which he appeared relaxed, often joking with reporters. He insisted that his rise to power within the ruling party would not lead to any changes in policy for either the ANC or the nation.

Yet he declined to answer questions about the fate of particular leaders within the government and party.

Among those whose future is uncertain is Finance Minister Trevor Manuel, whom many international investors credit with managing South Africa's surging economy with skill and fiscal restraint.

While Zuma praised Manuel's approach to managing government finances, the ANC leader's allies in the trade unions, the Communist Party and the ANC Youth League say Manuel has put the needs of business above those of the poor and unemployed.