In the midst of a serious political and economic crisis, Haiti's authoritarian government is using foreign aid to tighten its hold on this country, despite the efforts of its most important donor, the United States.

At a recent meeting of Western nations and agencies financing Haiti's survival, the donors pledged a record amount of aid to President-for-Life Jean Claude Duvalier. But while the donors had been unwilling to play politics with their assistance, the Haitian government, much to the chagrin of U.S. and other diplomats, widely advertised the aid increase as a broad endorsement of its policies.

Foreign missions here, which had welcomed a somewhat greater political freedom during the past year, where infuriated when the Duvalier government jailed almost all its prominent critics just days before the aid talks.

Then, during the donor meeting, Haiti engaged in an unusual test of wills with the United States by censuring the American deligate. When U.S. representative Allan Furman began to express concern about the "recent deterioration in Haiti's human rights environment," Haitian Planning Minister Edouard Berrouet immediately cut him short.

Human rights remarks were "not acceptable," said Berrouet, loudly ringing a bell. "Please pass to the technical part of your statement." Rather than walk out, the U.S. delegate obeyed.

The confidence of the government, foreign analysts agree, comes both from its reading of the new, conservative political winds in Washington and from assurance of international economic support.

With 90 percent of its population living below the poverty line and two-thirds of its land badly eroded, Haiti's growing population is sometimes described as one that is "slowly committing mass suicide."

The donor meetings began more than two years ago in an effort to pressure the government into stemming corruption and changing its budget practices to account for the nearly half of government revenues that go into "secret" accounts. The donor countries and agencies agree that little has been accomplished in that direction.

They have many times threatened to cut off the aid that keeps this country afloat, yet Haiti's massive need and their own rules for giving to the most desperate cases, have made the threats meaningless. The United States, Canada, France and West Germany, the largest donors, announced more projects for 1981, even though they privately say that the government badly mismanaged its economy and did not keep its promises to clean up corruption.

American aid, worth $33.2 million in 1980, will be increased with additional food donations. Precise details for next year's foreign aid were not yet available, but Haiti will get at least 20 percent more than the total $137 million of international aid it received in 1980. This gives its 6 million people the highest per capita assistance in this hemisphere.

The increase worries many development experts who argue that "more compulsive giving" is not what Haiti needs and the country cannot absorb it. "In 1980, only $70 million or at the most $80 million of the $137 million in aid could be absorbed," one knowledgeable foreigner here said.

In an effort to circumbent government rake-off of aid funds and to try to insure that assistance gets to Haiti's poor, the United States in several instances has developed "food for work" programs under which Haitian laborers receive their wages largely in meals. Many aid officials see the U.S. programs as among the least successful, arguining that only about half the food reaches the workers, it increases dependencey and provides free labor for wealthy landowners.

Haiti's recent massive crackdown against the opposition and its alleged squandering of aid money has once again highlighted the dilemma of how to help a starving people whose government apparently is not committed to improving the lot of the majority.

Carter administration officials who believed that aid to Haiti has been an effective instrument in helping to create the more liberal climate of the past few years now say despondently that the instrument is a very fragile one.

"The Haitians felt free to act when Carter lost," said one U.S. official.

There is no simple answer for the aid dilemma, diplomats here admit.

"If we cut aid because the Haitians throw their people in jail, it only tightens the vicious circle," said one European ambassador. "Then the economic situation worsens, there is more hunger and more protest and greater repression in the end."

Haitian officials say they detained about 50 persons at the end of November who were part of a "communist conspiracy." The number was believed to be much higher.

Since then, 12 journalists and moderate politicians have been expelled and an unknown number released. Last weekend, at least 17 people were still held, incommunicado and without specific charges. It was the largest sweep since Jean Claude Duvalier took over from his father in 1971.

But the foreigners footing Haiti's aid bill who at first took the arrests as an "ill-timed slap in the face" now concede it was really a "carefully timed, clever gamble" by Duvalier.

Just before the police action, the progovernment press gave broad display to a statement from France's Minister of Cooperation Robert Galley, who described Duvalier as the best possible president for Haiti.

The following day, West Germany's ambassador here announced his country would attach no political conditions to its aid. In that same week the International Monetary Fund extended new credits to Haiti despite violations of its agreement with the IMF, and Mexico added Haiti to the list of nine developing countries in the region that will get favorable financing when buying Mexican oil.

Armed with this show of support and Ronald Reagan's victory in the United States, Duvalier was able to move and red himself of all his important critics, diplomats here believe.

But some Americans here point out that the government's weakest point may prove to be the stream of Haitian boat people fleeing poverty and a system that gives them little opportunity.

This year alone, more than 30,000 Haitians landed in Florida in search for a better life.

"It may dawn on the American taxpayer that they are paying twice for Haiti," said one U.S. development worker here, "first to support the Duvalier regime and second to support the Hatian boat people in the U.S. and meanwhile both the number of millionaires and the malnutrition figures are growing here."