It was incorrectly reported yesterday that a holiday had been declared in Puerto Rico in honor of four newly freed nationalists who spent more than a quarter century in U.S. prisons for terrorist attacks on American politicians.

More bombs and terrorism may be necessary for Puerto Rico to achieve independence, but that is the U.S. government's fault, newly freed Puerto Rican nationalists said today.

More than a quarter century in prison has not softened Lolita Lebron, 59, and Oscar Collazo, 67, who told a cheering crowd at an evening rally that they will seek to unite the island's badly split independence movement when they return on Wednesday.

"First we will have to see how far American terrorism has gone in Puerto Rico, and then we will decide whether terrorism by our side is necessary," Collazo had told reporters earlier.

He was imprisoned in 1950 after an assassination attempt on President Truman in which a White House guard and a Puerto Rican were killed. President Carter freed him on Monday, along with Lebron and two other Puerto Ricans who had wounded five congressmen with gunfire from the House visitors' gallery in 1954. A fourth gunman in that incident died of cancer in 1977.

More than 2,000 cheering persons jammed the cavernous St. Paul the Apostle Church on Manhattan's West Side to hear the four promise independence for Puerto Rico. The president of the island's Nationalist Party, Carlos Velez Rickenhoff, told them it made him feel young again to look at Lebron. "She will be the head of the Republic" when there is independence, he promised.

Lebron had the crowd roaring when she told them, "We will stay here tonight. You are going to liberate Puerto Rico, Yes you, for all Puerto Ricans."

Earlier, at a press conference at the United Nations, Lebron reacted angrily to questions about the uses of violence by a Puerto Rican revolutionary group, FALN, emotionally telling reporters they should be ashamed of themselves for not raising the same questions with President Carter about the arms race.

"We cannot disavow people who stand for liberty," she said. "If they [FALN] use bombs, what can you do? I hate bombs, but we might have to use them."

She and Collazo blamed "American aggression and repression" in Puerto Rico for promoting their attacks a quarter century ago. "The United States did not become an independent nation by throwing flowers," Collazo said.

Their two colleagues, Rafael Cancel Miranda, 49, and Irvin Flores Rodriguez, 55, held a simultaneous press conference in a storefront action center in the heart of New York's Hispanic community on the Lower East Side.

Puerto Rico now has commonwealth status with the United States, a system that island factions agree needs drastic overhaul.

Backers of commonwealth status would like to loosen the ties to America, while independence advocates, now in four badly divided parties, want to cut those ties altogether.

The current governor, Carlos Romero Barcelo, is a strong advocate of statehood for Puerto Rico and plans a popular referendum in 1981 on the subject of the island's status. President Carter has said he will abide by the plebiscite. But both Romero and Carter face difficult election races before then.

The freed nationalists leave Wednesday for Puerto Rico, where a holiday has been declared in their honor.