Nicaraguan Indian rebel leader Brooklyn Rivera has become the first leader of a CIA-backed contra group to begin publicly announced peace talks with the ruling Sandinista Front.

But government and Indian sources indicated that the success of these neogotiations will depend on how many of the divided Indian insurgents he can persuade to stop fighting. An agreement with Rivera would be a blow to the anti-Sandinista forces and would also help the Sandinistas defend themselves against charges that they violate the civil rights of Nicaragua's Indians.

Rivera has clear control only over his own rebel faction, which is thought to number between 500 and 1,000 fighters. The major Indian rebel army, Misura, is headed by Steadman Fagoth and is thought to number about 2,000 guerrillas. Both organizations have received funds from the CIA.

Most of Nicaragua's Miskito, Sumo and Rama Indians live in the isolated eastern part of the country which had long been ignored by the Spanish-speaking people of the capital, Managua, and the rest of Nicaragua. The Indian population has been estimated at anywhere from 60,000 to 150,000.

When the Sandinistas came to power in 1979, they tried to organize a grass-roots Indian organization called Misurasata to convey Indian wishes to the government and Sandinista ideology to the Indians. But when antigovernment activity becan in the northeastern part of the country, the Sandinista Army moved into Indian villages and forced the inhabitants to move into resettlement camps. Thousands of Indians fled across the Coco River into Honduras and many joined the anti-Sandinista forces.

Fagoth and Rivera, both of Miskito Indian descent, were once leaders of Misurasata.

But both those men, and other Indian leaders, were arrested in February 1981 and charged with leading a separatist movement after they called for a larger measure of autonomy for Nicargua's Indian peoples.

The leaders were all freed within six weeks, but Fagoth left Nicaragua almost immediately to begin his war aganst the Sandinistas from Honduras. Rivera left in August of the same year, because the Sandinistas would no longer allow him to travel and organize Indians.

Rivera, a university trained mathematician and former Baptist seminary student, returned to Nicaragua Oct. 20, and spent 12 days here. He met with Sandinista leaders and traveled to Indian villages and resettlement camps talking about his decision to negotiate peace with the government.

"I bring you greetings from the fighters both in the north and the south," Rivera told the crowds in eastern Nicaragua.

About 25,000 Indians have gone to Honduras and Costa Rica since fighting began and many others have been moved to resettlement camps away from the Honduran border region. Rivera's promise that he is working to reunite the Indian community and lead Indians back to their traditional villages has met with enthusiastic emotional support.

"I am a symbol to these people of their loved ones who are in Honduras and Costa Rica, some of them fighting," said Rivera. "I tell them it is like dream that I am standing before them again and that if they support my initiative I may make their other dreams come true and bring back their family members."

Rivera, during his stay, negotiated an agreement that some Indians in resettlement camps would be allowed to move back to villages south of the Coco River. He also arranged for an exchange involving five prisoners of war.

Rivera has also resurrected the issue of Indian autonomy in the Indian communities, insisting that the Sandinista Army stay out of the villages, that traditional land titles be honored and that Indians be in charge of government programs in the region. Although no accords have yet been reached, Sandinista officials say that they are willing to deal with the autonomy issue in a more broad-minded manner than they were three years ago, even the touchy issue of tax-free Indian use of rich eastern woodlands.

"We understand what concerns the indigenous people," said Jose Gonzalez, chief internal security official in northern Zelaya province. "They want their religious, social, cultural and economic traditions respected and we agree they should be."

Before coming to Nicaragua, Rivera visted Honduras and although Fagoth was against the peace mission, Rivera insisted that many of the political and military leaders of the Indian rebel community told him privately they supported his decision. According to sources close to Rivera, there already has been a degree of low-level military cooperation between the two Indian rebel armies, and Rivera was leery of criticizing those people whom he wants to pull into an alliance. These claims have not been substantiated publicly by the Indian leaders in Honduras