By PETER KIHSS

Three Cubans, understood to be opponents of the regime of Premier Fidel Castro, were arrested last night in the Dec. 11 firing of a bazooka shell toward the United Nations Headquarters.

Chief of Detectives Philip J Walsh said each of the three was charged with endangering life maliciously by placing an explosive near a building, and with attempting to damage a building or a vessel, both of which are felonies. They were further charged with conspiracy, a misdemeanor.

Chief Walsh, identified the three men as:

Julio Carlos Perez, 31 years old, of 247 Audubon Avenue, a teletype repairman who has been in the United States for three years. He was booked as 29.

Ignacio Novo, 26. of 535 West 50th Street. a shoe salesman who has been here for 12 years.

Gullermo Novo, 25, his brother, of 1414 91st Street, North Bergen, N. J., a doorman. who has also been here for 12 years

Chief Walsh, Police Commissioner, Michael J. Murphy and District Atorney Frank D. O'Connor of Queens said the arrests resulted from intensive police work, including painstaking checkups on the sale of bazookas.

However, Stanley Ross, editor of El Tiempo, a Spanish-language weekly, asserted the three had agreed to surrender after discussing the affair with him and his associates.

Mr. Ross said the men had told him that "they could have hit the United Nations headquarters but purposely didn't." Instead, he said, they sought to stage a demonstration so as to take away newspaper headlines from Maj. Ernesto Che Guevara, Cuban Minister of Industry, who was addressing the General Assembly at the time.

When Chief Walsh was asked if they had tried to hit the United Nations buildings, he said only, "That's conjectural." District Attorney O'Connor, in reply to questions about motives, said this was a "matter of conjecture," and then added, "I suppose some misguided sense of patriotism."

Mr. Ross said the three were members of the Cuban Nationalist Movement, which has offices in Miami.

In Miami, Felipe Rivero, national director of the movement, which is also known as the Cuban Nationalist Association, said before the men were arrested that Ignacio Nova was his organization's national secretary general and that Guillermo Nova was delegate for New Jersey.

A "Julio Perez" is chief of the organization's "naval department." Mr. Rivero said.

Mr. Rivero said he knew nothing about who had perpetrated the bazooka incident. His organization, he said, had caused the explosion on the Cuban freighter Maria Teresa in Montreal last Aug. 9, and had staged a fight in front of the Cuban consulate here in 1960 and disturbances at the United Nations and the Organization of American States meeting in Washington this year.

"But we have made very clear our position not to do anything hostile in this country, anything that would put this country in a difficult position," Mr. Rivero said. "We try not to clash with American authorities."

Mr. Ross said the three men had told him and others at E1 tempo that they had bought the bazooka, a portable rocket launcher, for $35 in an Eighth Avenue shop and rebuilt it.

The police had earlier reported that the weapon had been identified by experts at the Array Proving Ground at Aberdeen., Md., as an 8.8 centimeter - equivalent of 3.46 inches in diameter - German bazooka rocket-launcher tube, manufactured in World War II.

The police said the bazooka appeared to have been sawed off from a five-foot length to less than three feet, and set up as a. sort of mortar with a clock-like timing device.

The shell was fired from the East River waterfront along side the Adam Metal Supply plant at 4-63 48th Avenue Long Island City. It landed in the East River about 200 yards short of the 38-story United Nations Secretariat building, sending up a 15-foot geyser of water.

Investigators said the bazooka had been elevated to about 20 degrees, so that the shell had traveled only about 800 yards. If it had been elevated at a higher angle, it could have carried as far as 1300 yards, and shattered the glass and concrete facade of the United Nations building, causing many casualties among the 5,000 persons there at the time.

Chief Walsh said the police had, investigated a number of individuals and had check intensively on the sale of bazookas. As a result, he said, the three prisoners were interviewed in the first week of the inquiry, but had to be released for lack of evidence. "However," he went on, "surveillance and investigation of them continued, and through this, we finally learned they were desirous of surrendering. Two of the men were picked up at work- today and the third came in as a result of phone call from the others. The men have made statements to the District Attorney and to us."

Mr. Ross said El Tiempo had been asked for help by the Bureau of Special Services of the Police Department and by the Federal Bureau of Investigation. As a result, he said, his reporters found the men and met with them five times in eight days

Yesterday afternoon, he said, the men agreed at his office at 178 Fifth Avenue to surrender to the police at 6 P.M. at the office of their lawyer, Peter James Johnson, at 120 Wall Street. Instead, he said, they were picked up before then.

Mr. Ross said he and his associates had told the men that the bazooka incident had hurt the anti-Castro cause, and they could help by identifying themselves and explaining their aims.

Mr. Rivero said in Miami that the Cuban Nationalist Association was formed Nov. l0 1959, at a New York meeting with seven members, including himself and Ignacio Nova.

The organization has "delegations" in such places as Tampa, Los Angeles and New York and "cells" in Canada and Cuba, Mr. Rivero said. Its main effort, he said, has been to "build up machinery" throughout the world against "all international expressions" of the Castro regime, including its commerce, artistic ventures and diplomacy

The three prisoners were booked at the precinct at 5-47 50th Avenue. Long Island City., at 10:50 P.M. They are to be arraigned today at 10 A.M. in Queen Criminal Court, 125-01 Queens Boulevard, Kew Gardens.

The felony charges could bring 25-year prison sentences on each count. The conspiracy charge could mean a 3-year term.

Commissioner Murphy said the case showed "a tremendous need for legislation" for better control of the sale of weapons.

The Dec. 11. detonation had been audible in the hall of the General Assembly. Major Guevara had been denouncing the United States. Windows rattled from the blast.

Shortly before, 50 anti-Guevara pickets had been marching; in front of the United Nations headquarters and a woman ran hysterically from the group it an attempt to force her way into the building with a seven-inch hunting knife. She said later she had wanted to assassinate Major Guevara.