Several U.S. banks were accused yesterday of undercutting the Carter administration's human rights policy by lending the military dictatorship in Chile almost $1 billion to shore up the Chilean economy.

An independent study, made public yesterday, charges that efforts by the administration and international lending agencies to pressure the Chilean regime into improving its human rights record were frustrated by Chile's ability to get badly needed financial help from the private banks.

The study said these loans have totaled $927 million since 1973 - the year when the government of President Augusto Pinochet came to power in a bloody coup that involved the killing of Marxist President Salvador Alende.

Chilean exiles and rights activists have charged the Pinochet government with practicing massive and systematic repression, including the alleged murder, torture and imprisonment of thousands of opponents.

Since the Carter administration took office last year, the United States, in an effort to put pressure on Pinochet, has cut off almost all direct U.S. financial aid to Chile. It also has used U.S. influence to impede Chile's ability to get loans from international lending institutions such as the World Bank and Inter-American Development Bank.

However, the study alleges, the Pinochet government has had little difficulty in evading these pressures because of the willingness of U.S. and European banks to give it the loans and credits required to keep the Chilean economy functioning.

The study cites six major American banks - Bankers Trust of New York, Chemical Bank of New York, the Wells Fargo Bank of San Francisco, Citicorp of New York, Morgan Guaranty Trust of New York and First Chicago - as taking the lead role in making and arranging loans to Chile during this period.

This information about the banks' role was developed by Michael Moffitt and Isabel Letelier, who wrote, the study for the Institute for Policy Studies, a private, Washington-based research organization.

Their spouses, Orlando Letelier, who was Chile's ambassador to the United States under Allende, and Ronni Karpen Moffitt, an institute employe, were murdered in the 1976 bombing of their car in Washington.Michael Moffitt, who also was in the car survived.

Elaborating on the study yesterday, Moffitt said the information on private bank loans had been obtained from a variety of sources and verified by the State Department as correct. Six banks, he said, he acted as managers in putting together consortiatype loans in which several private banks participated.

Moffitt listed these major consortia loans managed by the six banks as Bankers Trust, $180 million; Chemical Bank, $125 million; Wells Fargo, $125 million; Citicorp, $86 million; Morgan Guaranty Trust, $150 million; and First Chicago, $75 million.

These loans, together with smaller ones from other U.S. banks, have provided Chile with $927 million of its approximately $1.5 billion in private borrowing since 1973, the study said. The balance came from banks in Western Europe and Japan, the study added.

Moffitt and Letelier noted that Chile has turned increasingly and successfully to private borrowing sources during the period when governmental aid from the United States and other countries and agencies was drying up.

Their study said that, in 1976, when the U.S. Congress put a $27.5 million ceiling on aid to Chile, loans from private banks increased more than 500 percent over the previous year to $520 million.

Total private loans jumped to $858 million in 1977 and will reach nearly $1 billion this year, the study said. By the end of 1978, it added, private creditors will accounts for more than 90 percent of Chile's total borrowing.

The study said the Pinochet government has been able to attract these loans by steering the Chilean economy away from the socialist experiments of the Allende period and toward ultraconservative fiscal policy and a resurgence of private enterprise.

Such steps, the study said, appeal to the banks because it makes the Pinochet government appear a "good risk" that can be counted on to pay its debts. But, the study charged, the same economic policies also are having the effect of concentrating Chile's wealth in the hands of a few at the expense of the masses.

The study said the loans have helped the Pinochet regime meet its financial debts to other governments and international lending agencies.As a result, the study concluded, "the Pinochet regime has a green light to thumb its nose at international pressure . . . because the junta has private sources of financing at its disposal other than governments that have attached tough human rights criteria to their foreign assistance programs."