Rosaylynn Carter said today she had stressed her husband's "deep, deep commitment to human rights" in talks with Brazilian leaders.

The human rights issue was raised at a news conference here in which the President's wife was asked about a letter she had recived from University of Brasilia students charging that the military regime here had abused human rights.

The letter said students all over the country had begun demonstrating last month "to protest the arbitrary imprisonment of workers and students in Sao Paulo," Brazil's largest city. The letter also noted that the government had closed the University of Brasilia for the three days of her visit to this country.

Asked what she thought of the letter, she said, "I haven't studied it in detail. I'll be glad to take it back to Jimmy personally. I'm sure he'll be glad to receive a perspective on human rights from the students."

Later, a reporter asked, "Isn't simply taking the letter to your husband a cop-out?"

"Not at all," the First Lady retorted. "You presume a determination that I am not able to make. I have stressed here as I have stressed in every other country the deep, deep commitment that we have toward human rights."

She said she had "very good meetings" with Brazilian President Ernesto Geisel and Foreign Minister Antonio Azeredo da Silveira "and I have made clear to them Jimmy's position on human rights. I'm not avoiding the question."

Mrs. Carter, who is visiting Brazil as part of a seven-nation goodwill tour of Latin America, also disclosed that she had talked to Geisel about reprocessing nuclear fuel.

"There is going to be an international study in depth on this problem, and we hope Brazil will join in this study," she said.

The First Lady was referring to a study of recycling nuclear fuel that was commissioned by leaders of seven industrial nations attending an economic summit meeting in London early last month.

A source here said Mrs. Carter's comments with Geisel were aimed at convincing Brazil it should seek from an international source reprocessed fuel to run nuclear power plants and not try to produce such fuel itself.

Brazil, which imports 80 per cent of its oil, has signed an agreement with West Germany to acquire the capability to make its own enriched uranium and to reporcess used fuel.

The United States is opposed to Brazil's plan because a byproduct of reprocessing is plutonium, from which nuclear bombs can be made.

Asked her impression of Brazil's military regime, she declined to criticize it.

"The fact that I am here shows we consider Brazil to be a very important country in the developing world and want to cooperate and work closely with Brazil" she said.

Her comments were in keeping with extensive efforts by U.S. and Brazilian diplomats to downplay past differences between the two nations. Sources in both governments said it was significant that Geisel, who usually sees no one below the leve of head of state, talked with Mrs. Carter for 70 minutes today and is giving a banquet for her tonight.

In another development, Grace Vance, wife of Secretary of State Cyrus K. Vance, confirmed that the secretary will visit Brazil this fall, Mrs. Vance is traveling with Mrs. Carter.

Press reaction to Mrs. Carter visit has been mixed, but more favorable than not. O Globo, a Rio de Janeiro newspaper, carried a front-page editorial calling her mission "unorthodox" but said that "it must be considered important." O Estado of Sao Paulo and the Jornal Do Brasil in Rio did not print editorials but had extensive news articles on the visit.

A Brazilian feminist, Terezhina Godoy Zerbino, was stopped by police when she tried to give Mrs. Carter a letter as the First Lady visited the Brazilian senate later in the day.

The letter, shown later to reporters, told Mrs. Carter that she is seen as "the legitimate symbol of the American woman ready to join us in a fight for a just cause" and asked her to relay "the nature of our protest" to feminists in the United States.