Early yesterday morning, several foreign journalists were summoned to the Chilean government press office to discuss a number of bombings that had taken place the night before in central Santiago.

Although the bombs had been audible to anyone in the area and were mentioned in the morning newspapers, which attributed them to "terrorist" elements, the journalists were ordered not to publish the news outside Chile.

The punishment for such publication they were told, was "military justice," including possible imprisonment or expulsion.

The incident illustrates the near fanatical concern of the Chilean military junta with its image abroad, in this case its apparent desire to conceal the existence of any resistance, however small, to its authority.

Even more than concealing its problems, however, the junta seems preoccupied lately with getting credit at home and abroad for its achievements. Both tasks have proved difficult.

In the four years since it overthrew the leftist coalition government of Salvador Allende in a violent coup, the junta's international reputation has gone from bad to awful - increasingly tarnished with allegations of human-rights violations and political repression at the point of a gun.

More than any other Latin American nation similarly accused. Chile has become a pariah, open game for world criticism. It has been ridiculed in international forums, denied credit and threatened with economic isolation.

It is only recently that the strain of carrying such a burden has begun to show.

Chile is tired, said one pro government businessman, of "having Chileans treated like second-class citizens in the world." Besides, he said matter-of-factly, being a pariah is bad business.

Now that the Communist threat is considered vanquished, he said, "the business community here would like a long-term panorama in which profits can be made." That panorama has been clouded by bad publicity.

Whether in response to pressure from Europe and the Carter administration on human rights, pressure from the businessmen or simply because, as the junta itself says, most of its internal enemies have been subdued or eliminated, things are beginning to loosen up in Chile.

It began in November with the release of more than 300 prisoners held without charge under the state of seige imposed immediately after the coup and renewed every six months since.

In June President Gen. Augusto Pinochet announced a timetable for return to democracy withing the next decade. Last month he announced the dissolution of DINA, the feared state security police.

These actions have been met with skepticism both here and abroad as too-little, too-late or a mere subterfuge for more subtle repression, a fact that has caused government reactions ranging from confusion to fury.

"We've been trying to improve our image," puzzled one general, his hands turned up in appeal, "and no one is helping us.

"Three hundred prisoners released," he said, "and not a single word about it in the American press."

The prisoner-release story did, in fact, appear on the front pages of many major U. S. newspapers. But the government seems plagued with an attitude of permanent persecution, coupled with an intense suspicion of the American press and liberal establishment, which it blames for distorting news of the situation here.

The junta has been defiant so long that it now seems at war with itself over how far to bend to please the rest of the world, at times unsure of whether improved international relations will be interpreted as weakness.

"Carter spends 67 Minutes With Pinochet - the Longest of Five Presidential Meetings," screamed a front-page headline last week in the pro-government El Mercurio during Pinochet's visit to Washington for Panama Canal Treaty-signing ceremonies.

"Respect for Chile in the U. S." noted another in red ink. Apparently apprehensive over feared snubbing, the Chileans unabashedly described the trip as a huge success and probably the most important presidential mission of the past four years.

Santiago's newspapers - all pro-government - proudly noted that, in his meeting with Carter, Pinochet "neither asked nor begged for anything."

"First they have to convince themselves," one U. S. diplomat here said of the junta. "Then they have to convine the rest of the Chileans, and then the rest of the world."

It was elation ove the success of Pinochet's visit, informed observers here said, and a desire to maintain the first positive glimmers from aboard, that led to yesterday's somewhat heavy-handed news blackout over the bombings.

[The Washington Post was not among these summoned to the meeting at which correspondents were told not to report the bombings.]

The same kind of tentative relaxation, followed by occasional, often inexplicable crackdowns has characterized recent junta domestic policy, which one informed opposition source described as "quantitatively, but not qualitatively, much improved."

Except for areas around governmnet installations, only a few soldiers are visible in Santiago's bustling streets. Most of them are directing traffic or strolling with their sweethearts. While a 2-to-5:30 a.m. curfew is still in effect, it is likely that the government is simply waiting for the most opportune public-relations moment to lift it.

Only eight persons, allegedly detained in secret by government security agents, have disappeared this year. Last year's total was more than a hundred.

The cases, however, are just as mysterious, with as many investigatory dead ends as ever. Typical is that of Pedro Mella Vergara, a 38-year-old draftsman from Africa in northern Chile.

On May 4, according to church sources, Mella was leaving a bar, slightly intoxicated and shouting comments favorable to Peru - whose nearby southern border with Chile is a tense subject - when he was forced into an unmarked car by several men.

Mella's wife says the local military commander told her the next day that her husband had been detained by army security forces. The government denies that, and says it has no information on him. Except for one crytic telegram, telling her not to comment on his disappearance, she has heard nothing since.

Anywhere from 600 to 1,500 such disappearances have been reported since the coup, many with much more conclusive evidence of government involvement.

Human-rights groups say they believe that most of those people are dead and vow that they will never stop pressuring the government to account for them. But they are gratified, they say, that hearts do not pound quite so wildly now whenever there is an unexpected knock in the middle of the night.

Living under a dictatorship does not come easily to Chileans. "This country is not Uganda or Haiti," said one observer. "Chileans are not people who can't read or write or who have never seen a ballot box. They care about their institutions, and passionately want a say in the way they are run."

By the same token, although some say the junta has become power-hungry, military intervention has been very rare in Chilean history, and the military does not relish international humiliation nor hatred by its countrymen. On his return from Washington last week, Pinochet was greeted by enormous crowds whose presence was encouraged by a government order closing schools and businesses, and press hints that the welcome was expected.

Few junta critics here deny that the door has now been opened, and among the freedoms that have begun to appear is a new, if frail, spirit of dissent in even the most partisan pro-government publications.

Pinochet's election plan, presented in June, provoked a torrent of unprecedented public debate in the Chilean press, including and El Mercurio survery of 40 opinion leaders, most of whom criticized the President's lengthy timetable.

In a similar survey in the pro-government magazine Que Pasa, Juan Agustin Figueroa, a former member of the centrist Radical Party and the closest thing to a leftist to be allowed in print since the coup, modestly pointed out that Pinochet's plan, with the president giving himself the lion's share of electoral power, could lean to "absolute political rigidity."

In May, a case of alleged DINA abuses was given a rare display of fairly objectives media treatment. The case involved the son of a labor activist who testified that he was kidnapped by the police agency, tortured and made to accuse several family neighbors of the abduction.

Later the young man, while in "protective" DINA custody, said the neighbors really had taken him after all. In a third version, shortly before he and his family left the country for Canada, the boy returned to his original story.

An investigative article in Ercilla, a former opposition magazine recently taken over by government supporters, called the story "strange, contradictory and dangerous," and noted that its reporters had gathered evidence showing that the accused neighbors could not have been at the scene of the abduction.

The Chilean opposition views these small steps as important, but dampens it enthusiasm with the reminder that the junta has shown it can take away freedoms, just as quickly as it bestows them.

A case in point is the banning in March of the Christian Democratic Party following a clandestine party election. Although all the leftist parties that formed the Allende coalition have been banned since the coup, the Christian Democrats were, until March, only "suspended."