Brazil's authoritarian, anti-Communist military government has announced that it will censor all books and magazines sent to this country from abroad.

Police censors are to be assigned to post offices in major Brazilian cities to determine whether incoming publications "contain material contray to public order" or "run counter to morality and good standards of behavior." Books and periodicals that do not pass this test can be confiscated and, ultinately, burned.

Justice Minister Armando Falcao, who issued the decree, said it was done to combat "subversive and obscene" foreign authors. Brazil's inlectual community regards the move as an effort by the regime to increase pressure on Brazilian liberals.

The decision to invoke prior censorship is likely to focus immediate bad publicity on Brazil from abroad since it coincides with Rosalynn Carter's Latin American visit which includes two Brazilian stops. Relation between Brazil and the United States have become strained partly because of President Carter's continued defense of human rights U.S. State Department report that was critical of Brazils handling of human rights.

The only public hint that there was increasing government concern about what Brazilians are reading was a recent spate of accusations from several generals that there was "communist infiltration" in international news and artistic media.

Several years ago the Brazilian military leaders complained frequently about an alleged international conspiracy to "degrade the image of Brazil," and that was followed by a 1970 extra-constitutional censorship decree.

The new ruling is an extension of that 1970 decree, which gave the government the power to subject books and magazines - Brazilian as well as foreign - to prior censorship.

Ironcally, the Brazilian constitution now in force under the military government specifically prohibits that type of censorship, but the nation's rulers apparently have chosen to ignore the discrepancy.

The order was greeted with some criticism from inside Brazil itself.

The country's most influential newspaper, O Estado de Sao Paulo, called the order "one more document for fattening up international reports on humanrights violations in Brazil."

A Brazilian author and intellectual, Antonio Houaiss, compared the order with "the Great Wall of China," saying it will "impede the penetration into brazil of outside news and opinions and make us removed from what people overseas are saying about us."

Joaquim Bevilacqua, a congressman in Brazil's one legal opposition political party, declared: "Brazil has become an island, in all but the geographical sense.

The new decree could cause foreign magazines such as Time, Newsweek, L'Express and The Economist to disappear from Brazilian newsstands while censors read them to see if they contain anything considered subversive or immoral. American and European periodicals are a prime source of worldwide news for Brazilian intellectuals.

And if Brazil's definition of foreign periodicals includes newspapers - a point that is not clear - American tourists here could be deprived of their daily copies of newspapers from home, which routinely arc air-mailed to leading hotels. Native Brazilians who subscribe to such foreign publications also would be affected.

There already had been severe limitations on foreign publications in Brazil before the new ruling. Because of the 1970 censorship decree, Playboy, Penthouse and several other American and European magazines had been banned outright. And the book black-list here had grown to over 350 titles, ranging from "The Happy Hooker" by Xaviera Hollander to "Quotations from Chairman Mao."

Stories from the New York Times, the Washington post, the Los Angeles Times andRolling Stone magazine - now appear routinely in major Brazilian newspapers under translation and republication agreements.

Because Falcoa's censorship order specifically applies only to publications that come into Brazil by mail, these sources of foreign news probably won't be affected. The government can, however, censor any Brazilian newspaper whenever it wants.