Pope John Paul II, saying he had seen in Argentina "the fervent pleading for peace," prayed for an end to Argentina's war with Britain today before more than a million persons in the Buenos Aires district of Palermo.

In the culminating event of his quickly arranged, 32-hour visit to Argentina, the pope called on the cheering, chanting crowd that had spread through the city's Palermo Park on a brilliant, cool day to "make a chain of union, stronger than the chains of war."

"We want peace, we want peace," was the answering chant that spread through the huge, peaceful crowd in echoing waves as the pope raised his hand and smiled. Argentine officials described the gathering as the largest religious event in the nation's history.

John Paul made no direct reference before leaving Argentina for Rome this afternoon of the heavy new fighting at the Falkland Islands capital of Stanley, first reported by Argentine military officials this morning.

But in a series of messages at a meeting with church authorities, the mass and at Buenos Aires' Ezeiza Airport, he called on Britain and Argentina quickly to seek a diplomatic solution to the conflict.

"Let there be no hesitation in seeking solutions to save the honor of both sides and reestablish peace," he said before boarding his plane.

Although President Leopoldo Galtieri and the two other members of the ruling junta left their military headquarters to attend the two-hour mass at Palermo in civilian dress, there was no indication that the pope's strong appeals had affected the government's determination to carry on the conflict with Britain.

Interior Minister Alfredo Saint Jean told reporters shortly before ascending to the podium to take part in the Palermo mass that Argentines should have "faith and confidence" in a "final victory" over Britain. Asked about the impact of the pope's visit here, Saint Jean said he expected it to help the country "achieve a peace with justice, respect and dignity."

Throughout the country, officials and many average citizens seemed to interpret the pope's calls for peace as support for a solution that preserved Argentina's claim to the Falkland Islands.

"Now, with the pope, we can win the war," exclaimed one woman after hearing the pope's homily at Palermo.

Government officials and national political leaders clearly hoped that the pope's visit here would rally national unity and support for the long-running and increasingly costly Falklands conflict. Television broadcasts of today's mass were interrupted for military bulletins on the fighting, and government-sponsored announcers led patriotic chants and cheers over loudspeakers at each of the gatherings attended by the pope.

In Palermo Park, leaflets littered the broad avenues leading to the round central circle where the mass was held, reading, "If you want peace, smash the imperialist aggressor," and signed "Workers Politics." At times during the visit, cries of "Long live the pope" and "Long live the church" turned to "Long live the fatherland" and "Long live the Malvinas," Argentina's name for the Falklands.

For many of the hundreds of thousands who gathered early this morning on the grass lawns of Palermo Park or lined the pope's routes along the broad avenues of Buenos Aires, however, the event seemed little more than a chance to celebrate and cheer a revered figure at a time when the country has little else to cheer.

"This is a very sad time for our country, an ugly time," said one middle-aged man who traveled into town from a working-class suburb of Buenos Aires to attend the mass today. "No one wins in a war. But it is a moment of peace to see the pope. It is someone we all can love."

Warmed by balmy sunshine after more than a week of drizzly, cold weather, Palermo Park began filling yesterday for today's mass. Thousands of persons, mostly youths, camped out overnight near the high marble monument to Spanish immigrants at the park's center, chanting and singing a special song written for the pope's visit entitled, "Thank You, John Paul."

Working frantically in the two weeks after the pope's special trip to Argentina was announced, workers had constructed a huge stage in front of the monument, straddling the intersection of two wide avenues that cut through the park. Above it, a large, white cross was suspended over the center altar.

Dozens of the spectators fainted or collapsed in the crushing crowds, and teams of volunteers spent the day shoving through the crowd carrying the casualties on stretchers. This evening, unofficial reports said that at least three persons had been injured seriously.

As the pope arrived, the crowd dissolved into a sea of waving flags and banners and chants of "John Paul II, all the world loves you." Throughout the mass and the pope's homily, even those far from the stage and the loudspeaker network were respectfully quiet, starting to cheer only when the pope addresssed the crowd at the end of his talk.

As in his messages yesterday in Buenos Aires and at the national religious shrine of Lujan, John Paul was forceful in calling for peace but carefully avoided references to politics or the human rights themes he has raised in addressing Argentina from afar.

In a meeting this morning at Buenos Aires metropolitan cathedral with Argentine bishops and cardinals, along with church authorities from Chile and Colombia, the pope described his mission to visit both Britain and Argentina in time of war as "difficult" but "urgent."

"I knew very well when going to Great Britain" for a six-day visit earlier this month, the pope said, "that someone might interpret such a mission in a political sense . . . . Nevertheless, I judged that faithfulness to my own ministry demanded me not to stop in fear of possible wrong interpretations."

The pope, speaking Spanish throughout his visit here, urged that church authorities seek union and a common cause of peace with "your bishop brethren" in Britain and, for the second time in his visit, reminded church leaders that patriotism must be tempered by broad religious unity.

At Palermo, the pope followed yesterday's somber homily on suffering at Lujan with a message focusing on the redemptive powers of Christ, stressing in a loud voice that Christ's body and blood "bear death and at the same time life."

Then, looking over the crowd, John Paul called on Argentine youth, saying, "I've seen in your eyes the fervent pleading for peace that arises from your spirit."

"Join with the youths from Great Britain," John Paul said amid rising cheers, "who on recent days have applauded with equal sensitivity every invitation to peace and harmony. Let no hatred wither the generous energy and the capacity of understanding we all carry inside."

Then, the pope closed his eyes and prayed with the crowd for those who have died and their families, both in Britain and in Argentina.