A prestigious coalition of anthropolgists, human rights groups and American Indians is seeking to persuade the Brazilian government that greater efforts are required to save the last large tribe of unacculturated Indians in the Amazon basin.

Some 17,000 Yanomamo Indians living along the border between Brazil and Venezuela are threatened by highway and uranium-mining projects on the Brazilian side.

While Brazil has announced plans to create a reservation, anthropologists, and others contend it is too small and has a flaw that will prove fatal to the Yanomano -- the 12 million acres are broken into 21 parcels, many of them allegedly too small for the survival of the foraging Indians.

Joining in support for a bigger, contiguous reservation are the 12,000-member American Anthropological Association, two Washington anthropological societies, the Insitute for the Development of Indian Law and the Letelier-Moffitt Memorial Fund for Human Rights.

Leading the coalition is Shelton H. Davis, director of the Anthropology Resource Center in Boston, who has written a book on the impact of Brazil's development efforts on the Indian population.

At a recent meeting that drew 250 persons to the Carnegie Institution here, Davis detailed a pattern of "disease, death and destruction" of the Yanomamo since the start of Brazil's Northern Perimeter Highway in 1974.

Davis said that the Brazilian government promised to consider the expanded 16 million-acre reservation, originally proposed by a Brazilian citizens' group last June, but a response promised for September has yet to be forthcoming.

One development this month bodes ill for the project: the main advocate of expanded project within the government has resigned. Replacing the official as head of the National Indian Foundation is an Army colonel who formerly was head of security for Brazil's state mining company.

Linguist Ernest migliazza, who has studied the Yanomamo while living with them for over 15 years, described a primitive socity admirably adapted to survival on the often unproductive soil of the region.

"While we agree that the indigenous people should not remain isolated as museum pieces, we also suggest that they should be integrated into the national life by a slow and humane process" that would limit the current devastation by disease, he said.

Kirke Kickingbird, director of the Institute for the Development of Indian Law here, said:

"The desire for the establishment of reservations by Indians was not, and is not, a step into the past [but] a deliberate decision to control the pace of growth and change" of a society whose very survival until now proves its dynamism.