JOHANNESBURG -- The African National Congress has emerged from its first national conference inside South Africa with its leadership badly shaken by rank-and-file discontent and militancy and with the course of talks on constitutional reforms now very uncertain.

The militant wing of the ANC, deeply suspicious of negotiations between the ANC leadership and the white minority government, has gained considerable support at the expense of moderates within the organization.

Elections for a new national executive committee at the organization's next full membership meeting in June are certain to see many in the ANC old guard thrown out and a younger, more militant leadership elected. One likely result would be a tougher bargaining stance with the government in talks aimed at ending South Africa's apartheid system of racial separation.

Some South African and outside analysts already are predicting that one member likely to rise quickly to a top leadership role is Chris Hani, the outspoken ANC military chief of staff.

In this sense, the conference may prove to have been a watershed both in terms of the shifting alliances within the ANC and the way black groups will now proceed in their dealings with the quest for a transfer of power in the government.

Members of the ANC's national executive committee were lambasted by the rank and file for both their secretive style of leadership and their lack of concrete results from seven months of periodic talks with the government of President Frederik W. de Klerk.

ANC Deputy President Nelson Mandela came in for sharp criticism for holding a series of secret talks with de Klerk, for concessions he has made to the government so far and for his occasional use of old-style African authoritarianism.

The three-day ANC conference saw the clash of two very different styles of leadership and two different constituencies coming together for the first time in 30 years. On one side were the ANC's formerly exiled leaders, used to taking decisions on their own in secretive conditions and with little accountability to anyone for their mistakes and failures.

On the other side were ANC members who lived and worked inside South Africa, braving the bullets, dogs and whips of the South African police to mobilize black townships and develop a grass-roots-democracy approach toward decision-making.

Mandela was moved to remark in his closing speech that he had hardly heard a kind word spoken about any ANC leader throughout the conference -- the first legal ANC conference held inside South Africa since 1959.

Ironically, one of the main causes of the militant backlash within the ANC appears to have been the de Klerk government. Many local and foreign analysts say the government adopted an initial strategy of deliberately seeking to exploit the ANC's organizational weaknesses for short-term gains.

The government seized upon the ANC's early disarray and the apparent willingness of its leadership to strike risky deals. At the same time, it has entered into agreements that have subsequently become bogged down in bureaucratic red tape, according to these analysts.

The result has been a distinct souring of the negotiating atmosphere at a time when trust-building would seem to be crucial for success.

The main deal struck between the government and the ANC so far has been the agreement of the ANC to suspend its "armed struggle" in return for the release of 600 to 3,500 political prisoners and the return of 40,000 or more exiles.

But the government feels the ANC has simply replaced its armed struggle with a campaign of "mass action" in the streets, while ANC leaders face the stark reality that they have little to show so far by way of released prisoners or a return of exiles.

"Whether the delay is a deliberate attempt by the government to frustrate the ANC is a subject of dispute between the two parties," remarked Business Day in an editorial this week. "What neither appears to have realized until the weekend, though, is the degree of frustration and anger their inaction has led to."

The major black daily, the Sowetan, agreed: "The conference brought out the anger and impatience that is festering within the black community. There is a suspicion that . . . de Klerk has his own agenda, that of retaining white domination in a new form."

Now the ANC has hardened its demand for an elected constituent assembly to draft a new nonracial constitution. Facing elections at its June meeting, it is unlikely to be in the mood for compromise.

De Klerk, on the other hand, has ruled out an elected constituent assembly -- or an interim mixed black-white government -- saying such arrangements would effectively strip whites of power.

But the ANC leadership did push through the conference a mandate to continue "talks about talks," and Mandela successfully defended his right to continue his "confidential discussions" with de Klerk.

Those discussions will now take place in a different atmosphere, however. As the Business Day editorial remarked, when de Klerk and Mandela hold their next private meeting, de Klerk "will know that Mandela will have risked the ire of his membership to be there at all."