A Rand Corp. study on U.S. arms sales to Latin America has asserted that the Carter administration is using a double standard in its policy of linking human rights to U.S. military and economic aid.

The study says that some important recipients of U.S. arms assistance, notably Iran, are treated with undue consideration by the Carter administration despite human rights violations while several Latin America governments have seen their U.S. military assistance curtailed.

As a result the study says, some of America's oldest allies such as Brazil are pressing ahead with development of domestic arms production and are also looking for alternate sources of weapons supplies.

The study, written by David Ronfeldt and Caeser Sereseres, also regards as questionable the U.S. view that Latin governments are spending excessively on weapons and thus seting off a dangerous arms race.

"By most quantitative indicators, Latin America remains a relatively lightly armed region where military expenditures and acquisitions have grown rather slowly, compared to the developing world at large," they say in the study. Ronfeldt and Sereseres have participated in previous Rand studies of the Latin American military that have influenced U.S. policymakers.

The researches point out that in the "1973-75 period Latin America represented 2 per cent of the (U.S.) grant military assistance program, 2 per cent of foreign military sale orders" and 4 per cent of commercial sales.

Yet the area has borne the burnt of U.S. policy objectives ranging from encouragements of democracy to protection of American investments and restriction of Communist, or any outside, influence.

The area is, they say, a "a dumping ground for restrictive and discriminatory U.S. legislation that expresses principles wounded more seriously eslewhere in the world - but too difficuly to apply with out compromise because of the Soviet threat or some other compelling U.S. national interst."

While lauding the new focus on human rights as "a proper and useful emphasis for U.S. foreign policy," the authors note that "it seems most difficult to apply" in such important countries as Iran or South Korea. "Therefore, it would not be surprising if once again Latin America ends up bearing the brunt of the 'solution.'"

Looking at past congressional efforts to inculcate "liberal democratic practices," the authors say these "paternalistic measures proved to be relatively ineffective."

Brazil, they note, has been a target of human rights reaction yet the results may not have been as intended: "Brazil's relations with its neighbors have been smoothed by U.S. criticisms . . . which have served to disabuse the Brazilian government of its former unwanted image as a subimperial agent of the United States in South America during the Nixon Ford administrations."

Ronfeldt and Sereseres found that past U.S. restrictions on arms sales to Latin America helped preserve the regional peace that existed from the end of the Peru-Ecuador conflict in 1942 until the EI Salvador-Hondruras 'soccer war' in 1969.

"In the current international and regional environment, however, it is no longer feasible for the United States to dominate hemispheric military relations and arms transfers. Most governemnts, in Central as well as South America, have learned to be wary about the reliability of U.S, support in case of local conflict." Hence they are determined to diversify their arms supply.