As Pope John Paul II carries out a celebrated visit to Britain, overwhelmingly Catholic and relentlessly nationalistic Argentina has watched with all the jealousy and occasional spite of a spurned suitor.

Both the hostile reaction to the visit to Britain and attempts here to attach political significance to the pope's mission in Argentina on a trip here next month are threatening to poison what otherwise would be a momentous national event for this country.

Catholic Church leaders here have issued daily announcements stressing the "pastoral" nature of the pope's trip to Britain and seeking to rally enthusiasm for the hastily scheduled visit to Argentina next month, the first journey here by a pope.

The pope's trip to Britain is an obligatory religious mission, Cardinal Pedro Aramburu explained this week, while the two days in Argentine, June 11 and 12, will be "an expression of love" for a country where more than 80 percent of the population is Catholic.

But the consoling explanations--which have included a letter from the pope--have not seemed to soothe the sense of outrage among the many Argentines who believed the pope supported their cause and would call off his trip to Britain.

"The decision of the pope to go to Great Britain at this time," a prominent former government minister, Rear Adm. Jorge Fraga, said bluntly, "is a profound error."

The pope's initiative has come as something of an embarrassment for the military government, which has long identified itself as a Christian cause fighting against the "decadence" of the West and especially British "colonialism." It has posed particular problems for the Argentine Catholic hierarchy, which has not only fervently supported the occupation of the Falklands, known here as the Malvinas Islands, but is a key ideological source for the country's nationalism.

"I regret that perhaps there are going to be many Argentines who will not have sufficient tranquility and depth of vision to distinguish" between the political and "strictly spiritual" aspects of a pope's activity, said one archbishop, Candido Rubiolo of Mendoza, this week.

Rubiolo's remark applied not only to the angry attacks on the pope that could be heard Wednesday when news of the trip broke, but to the quick efforts by many sectors here--including some church leaders--to use the papal visit to Buenos Aires to justify Argentina's claims over the South Atlantic islands seized last month.

"We Insist: the Pope Could Go to the Malvinas," said the banner headlines in the newspaper Conviccion yesterday, summing up the wishes of nationalists and the Argentine military.

The turmoil over the pope's activities is not the first time Argentina's highly conservative Catholic hierarchy has found itself in an awkward position on causes dear to its followers.

Most recently, many Argentine Catholic leaders who backed the military's "dirty war" against internal opponents were upset when Pope John Paul II spoke out in 1979 on behalf of those who had "disappeared" and asked for a "speedy clarification" of their cases.

During the last year, the Catholic leadership in Argentina has moved to distance itself discreetly from the military government and has spoken out more strongly on violations of human rights. But, like the political and labor leaders directing opposition to the armed forces, prominent church officials here have been quick to endorse the military's invasion of the Falklands and its determination to defend them.

Archbishop Vicente Zaste, one of the most outspoken of the government's critics on human rights, recently defined the South Atlantic conflict as "a threat to our fatherland."

Now, with many Argentines already turning bitter over what appears to be a losing cause, local church leaders' explanation of the pope's presence on enemy territory have been marked by distinctly defensive tones.

Aramburu, who returned from Rome this week with the news of the pope's plan, conceded that "this trip by John Paul II could have produced a bad impression here" but hastened to add that the visit was necessary to resolve "a difficult psychological situation for Catholicism and for the pope himself."

Various church leaders also have implied that while the pope's visit to Britain has no political significance, his presence in Argentina will be a different matter. Italo di Stefano, the archbishop of the province of San Juan, declared that the pope "will show the word of peace" to Britain "in favor of Argentina."

Government leaders have shown far less hesitation to mix politics with the Vatican. Interior Minister Alfredo St. Jean, hosting a lunch for papal representative Achille Silvestrini on Thursday, opened his message of greeting by saying: "It is a great satisfaction for my government to have you in our country, especially . . . when Argentina is fighting to defend its territorial integrity that anachronistic colonialism has pledged itself to break."

Meanwhile, the country's progovernment newspapers are giving short shrift to the pope's activities in Britain.

"The Pope Spoke of Peace; London Doesn't Forget the War," was the headline in the paper La Nacion today. "The Visit Is Politicized," announced the paper Clarin, explaining that the pope's word had filled both Britain's Catholics and its Anglicans with "a feeling of guilt."