Argentina's military command today treated the massive air attacks on British warships yesterday as a major victory, and said that its ground forces on the Falkland Islands had shot down two British helicopters.

The Joint Chiefs of Staff said that Argentine Army forces had fought with British troops near the British landing site on East Falkland Island today, downing the two helicopters and seriously damaging two others. The statement said casualties among British forces had not been determined but that there had been only one survivor from the two helicopters shot down.

The military command said that Argentine troops "of a high level of training" were carrying out harrassment operations around the British base and that Argentine armored units were patrolling around the area. It said Argentine forces "retain their combat ability intact."

In other communiques during the day, the Joint Chiefs of Staff described the sinking yesterday of a British destroyer and transport ship as the culminating blow in four days of air raids on British forces around the Falklands. The military command claimed that 22 British ships and 33 aircraft had been damaged or put out of action by Argentine forces.

The announcements, which pictured Britain's South Atlantic task force as having lost the greater part of its fighting strength, seemed intended to compensate for the tide of bad news here earlier this week on Britain's success in establishing a beachhead on East Falkland Island with at least 2,000 troops.

President Leopoldo Galtieri, returning from a tour of military installations along Argentina's southern coast, declared that yesterday's air attack, falling on an Argentine national holiday, "had made the 25th of May another landmark in history."

Galtieri said there was no doubt that "the bloody events we are living through . . . will live as pages of glory in our history."

Other military officials today emphasized the high price they said Britain was paying for its attempt to force an Argentine occupation force off the Falklands, and Gustavo Figueroa, the chief of cabinet in the Foreign Ministry, said he believed the losses "could make Great Britain want to negotiate."

Figueroa, speaking in a radio interview from New York, said he expected that new negotiations between Argentina and Britain conducted by United Nations Secretary General Javier Perez de Cuellar could "end up well."

But diplomatic officials said that Argentina's interest must now focus on bringing more direct international pressure on Britain through the meeting in Washington Thursday of the signatories of the Inter-American Treaty of Reciprocal Assistance.

Argentine Foreign minister Nicanor Costa Mendez is expected to make a strong presentation of Argentina's position to the 21 American countries bound by the treaty, and possibly ask for a resolution condemning Britain and calling for an end to economic sanctions against Argentina by the United States, government officials said.

In Buenos Aires today, papal envoy Achille Silvestrini announced that Pope John Paul II would visit Argentina June 10 and 11, shortly after his visit to Britain. He added that the pope was not now attempting to act as a mediator in the eight-week-old conflict.

"The pope understands well that at this time he could not carry out a visit to Great Britain without also soon going to Argentina, although briefly," Silvestrini said.

Interior Minister Alfredo Saint Jean said after meeting with the papal envoy at Buenos Aires airport that the pope's visit "cannot be anything other than a promise, and perhaps an augury, of peace."

As several newspapers headlined the announcement of the first visit by John Paul II to this overwhelmingly Catholic country, excitement over the event seemed muted by disappointment that the pope had not called off his visit to Britain, a move widely anticipated here.

The announcement of the impending papal visit was somewhat overshadowed by a long series of announcements from the military command reporting on yesterday's actions by the Argentine armed forces. For the past several days there have been only sporadic and generally late-night announcements.

In a communique this afternoon, the military command said that since May 1, when British forces launched their first attacks on Argentine positions on the Falklands, Britain had lost 21 Sea Harrier planes and 12 helicopters, and that six ships had been sunk.

In addition to the two destroyers, two frigates, and a supply ship that Britain acknowledges were destroyed, the Argentine command said another unidentified frigate had been sunk. The communique also claimed three "frigates or destroyers" and another transport ship had been seriously damaged and 10 warships, a support ship and another unspecified vessel had been damaged by Argentine action.

According to the official reports, the destroyer Coventry was hit yesterday by bombs from Argentine planes, while the transport ship Atlantic Conveyer was sunk by French-made Exocet missiles fired by Super Etendard planes. It was the first time Argentine has reported using this sophisticated French-made plane or the Exocet missile since the British destroyer Sheffield was sunk by an Exocet earlier this month.

The Argentine report described the Atlantic Conveyer as the greatest loss of the task force, saying it was carrying an undetermined number of Harriers.

The series of early communiques also said one man had been killed and two wounded in an attack by British planes on the Coast Guard vessel Rio Iguzao near the Falklands. The communique, which did not say when the action took place, added that one Sea Harrier was shot down during the skirmish.

The military command offered no report of total Argentine casualties during the last three weeks of fighting or of losses to its air forces during the massive raids on the British.

A report in the progovernment newspaper La Nacion said that while Argentine troops had moved away from the British camp, small groups remain as spotters for Argentine artillery, which was said to be continuing to bombard British positions.

Defense Minister Amadeo Frugoli reiterated the military's official position that the British invasion force "is totally controlled" by Argentina. In a radio broadcast, Frugoli said "there is not great concern in this area" because "we're talking about a small area, surrounded by ridges that are our natural limit" to expansion of British control.