The kidnapers flashed yellow cards like those that once identified Argentine security forces. They carried .45-caliber pistols and clubs strapped to their wrists with leather thongs. And they communicated from their customized Ford Falcons with sophisticated radios linked to a central dispatcher.

The abduction this week of six foreign journalists over a period of two days again confronted Argentina's military government with the specter of its own dark past--a past that the military, even in its moment of greatest public support here, cannot seem to purge.

Both the technique and the equipment that the journalists described are vividly familiar from the years of the government's "dirty war."

In the late 1970s, Falcons with covered license plates cruised the streets of major Argentine cities almost nightly and between 6,000 to 15,000 people disappeared from sidewalks or their homes in the same manner as the journalists.

While the reporters were released unharmed, most of the thousands who disappeared in the "dirty war" have never been seen again.

Now, with the abductions and the retention by Britain of an Argentine military prisoner allegedly linked to several disappearances during the "dirty war," the government's human rights record is threatening to become a major obstacle in its campaign for international support against Britain.

"It has to be said very frankly that a great part of the difficulties that Argentina encounters in various European countries in the comprehension of its undeniable territorial rights originate in the bad image it has because of the problem of human rights," the leading moderate daily Clarin said in an editorial Thursday.

For Argentine government officials, the journalists' abduction was an embarrassing reminder of the military's past alleged excesses. "Here we are trying to make good public relations, and this happens," said Gustavo Figueroa, the chief of the cabinet in the Foreign Ministry, after a British television crew was kidnaped Wednesday.

Later in the week, the French and Swedish governments asked to interrogate Alfredo Astiz, a captain in the Navy still being held by Britain after being captured April 25 on South Georgia Island.

Astiz has been linked by rights organizations here to the disappearance of two French nuns and a Swedish teen-ager in 1977. The publicity surrounding his detention comes at a time when the Argentine government had hoped sentiment in Europe was beginning to turn against Britain.

For human rights groups here, the damage to Argentina's image abroad is not as serious, however, as the possibility that the once-feared security apparatus used by the Argentine military in the past to combat terrorism still has not been dismantled--or continues to exist outside of the government's control.

The issue had already resurfaced here this week with the appearance at the Interior Ministry of several hundred persons, many of whom had traveled from the interior of the country, seeking information about missing relatives.

Argentine Interior Minister Alfredo Saint Jean announced in March, at a time when U.S. officials were studying Argentina's human rights record, that families would be given individual briefings by government officials and pledged what he called a "definitive solution" to the issue of the disappearances.

But when the families went to the ministry Monday, they were told that the building was closed to be disinfected and that the promised information would be provided at "a later time."

"It was not a serious promise, although naturally it raised the hopes of many people," said Emilio Mignone, a leading human rights activist here. "They the government did it because they were weak then, both to help them internationally and on the internal front." That incident, combined with the journalists' seizure, has led several civilian leaders here to call on the government to clear up the problem of the missing people before it destroys Argentina's diplomatic position in the South Atlantic crisis.

"Whatever possibility that the crime against the journalists appears as an ugly institutionalized system" should be "torn out by the roots," said the right-wing morning daily La Nacion in an editorial yesterday.

But for the military government, which has labeled the abductions as a damaging blow to the Falkland Islands cause, the solution is apparently not so easy.

Interior Minister Saint Jean and other high government officials have suggested that the abductions could have been carried out by forces determined to destabilize the government. He raised the possibility of involvement by the remains of leftist organizations or even by foreign agents.

But so far, the government has made no arrests nor produced any evidence of suspects. The same lack of success followed the disappearance and death early this year of a young Argentine woman in a case that was similarly disowned by authorities.

The three journalists from Thames Television of London seized Wednesday afternoon near the Foreign Ministry said they were clearly in the hands of experienced professionals.

"These were people who have done this kind of work before," said Julian Manyon, a reporter with the Thames Television team. "They knew every detail."

Identifying themselves as police, the men who abducted Manyon, Trefor Hunter and Edward Adcock already had prepared their Argentine-made Ford Falcon for such an operation. Even the window handles in the car's back seat had been bound with cords, the journalists said, in order to prevent any possibility of screams for help.

Manyon said in an interview that he was forced to lie on the floor in the back of the car, and that his captors' chief concern was that the tops of his knees not appear over the edge of the back window as a possible giveaway.

Government apologies for this week's incidents also echoed the past. During the "dirty war," Argentine officials denied knowledge of the abductions or the victims and at times deplored what were called "excesses," while seeming to indicate that security forces had gotten out of control.

This week's events thus raised again for some human rights activists here a central question in Argentina. As Manyon put it, "Either the government is not in control of all the organized elements in the country, or we are all being made fools of."

In either case, the abductions would appear to be a serious problem for the military government. Argentine President Leopoldo "Galtieri and Saint Jean said they did not know who was doing this, but they were afraid of the consequences of it," Manyon said.

Other captured journalists, including a television team from New York's WNEW, said they were told by Saint Jean that the abductors could have been former state security men or even present police members. "There was something said on the order of 'Old habits die hard,' " one of the journalists said.

Human rights activist Mignone, who heads the Center for Legal Studies, a group that attempts to help families of prisoners and the missing people, marked the sixth anniversary today of the disappearance of his own daughter, Monica. She was a 24-year-old social worker and member of a political youth group at the time of her disappearance.

Mignone said the Falklands crisis had not raised his hopes of gaining news of her fate.

"The military cannot give information on these things, because they are giving information on themselves," he said. "When the crisis ends, they may try to use the deaths of the soldiers to cover all this and put an end to it."