An FBI undercover operation based in Miami has cracked a nationwide conspiracy to control the multibillion-dollar pornogrpahy industry, federal officials said yesterday.

A federal grand jury in Miami returned indictments against 45 persons from 10 states, following a 2 1/2-year investigation in which FBI agents opened a phony mail order house in Miami to make contact with the pornographers.

This new FBI drive was revealed on a day the governor of Louisiana and other high-level officials in that state were called before grand juries investigating alledged bribes and bribe attempts resulting from another FBI undercover operation, codenamed Brilab. [Deatils on Page a10.]

In addition, in New York a federal prosecutor responded to a swirl of controversy by denying that he leaked to the press information that led to premature disclosure of "Abscam," a third FBI undercover operation. "Abscam" is the "sting" in which seven House members and a senator were said to have been videotaped either taking cash or agreeing to take cash in return for political influence. [Details on Page A10.]

Among those charged with conspiracy and interstate transportation of obscene material yesterday were four men reputed to be the country's major traffickers in dirty books and movies. They are Rubin Sturman of Cleveland, Michael (Mickey) Zaffarano and Robert (Debe) Di Bernardo, both known as organized crime figures from New York, and Harry Mohney of Duran, Mich.

Zafarrano died of an apparent heart attack yesterday in New York just as FBI agents were trying to serve him a warrant, officials said. The others accused could not be reached immediately for comment.

The same investigation resulted in additional indictments againt 13 persons of film-pirating charges. They allegedly stole and made illegal videotape cassettes of such major motion pictures as "Star Wars," "The Godfather" and "Snow White and the Seven Dwarfs."

The pornography indictments were described by federal law enforcement officials as the largest single attack yet on the pornography industry. "We feel we've knocked out the entire major production and distribution chain in an organized crime controlled industry," a top official said.

Some Justice Department attorneys acknowledged that questions were raised about the worth of trying to enforce obscenity laws because they usually rank low in priority when it comes to allocating limited federal manpower.

A lawyer familiar with the case said: "We didn't go out trying to enforce morality. We were looking for industries controlled by elements of organized crime, and felt pornography was one of them."

A defense lawyer said last night that he was outraged to have his client lumped in the indictment with alleged organized-crime figures.

Richard Chesney of Oakland, Calif., said, "It appears to me that the Department of Justice attorneys in Florida have orchestrated this case to paint every defendant with a brush of organized crime even though they are not connected with organized-crime figures in any war nor have they had any involvement in most of the acts alleged."

Chesney said that his client, Roland Boudreault, openly distributes pornographic material from San Francisco. He said the FBI hardly needed an undercover operation to determine that.

Although word of the FBI's "Brilab" and "Abscam" operations leaked prematurely to the press, yesterday's undercover operation was disclosed by public announcement of the indictments.

A top FBI official said in answer to a question that the timing of the cases was in no way contrived to coincide with upcoming budget hearings in Congress. The bureau has about 50 such major undercover operations now in progress. "They're just starting to be fruit," the official said.

The Miami undercover operation -- called "Miporn" by the FBI -- began in August 1977 after the bureau took over a similar storefront operation from Dade County organized-crime investigators.

The original base of operations was a warehouse called Golde Coaste Specialties Inc.Is was made to appear to be a mail order house dealing exclusively in pornographic material.

Two undercover agents began infiltrating the pornography industry, officials said, and eventually traveled all over the country meeting top manufacturers and wholesalers.

At times the leaders of the illegal industry met at convention settings. The indictment said, for instance, that 22 of those charged met in Las Vegas early last month.

The alledged pornographic kings would use their own cover, a ligitimate film distributor or electronics show, to attend such meetings, according to one official.

The indictment alleged that it was part of the conspiracy for the leadership to control the industry by establishing "watch lists" of suspected government agents and to use threats and force to collect debts and enforce their own ban of unauthorized duplication of the allegedly obscene films.

At one point in the undercover operation the two FBI agents had to leave the warehouse because of threats from some of their distributors. "They were late paying their bills and the boys didn't like it," a source said.

Officials emphasized that the FBI agents did not actually sell any of the films or magazines they bought. And they said Miporn produced some side benefits.

In one instance last May, the agents were able to use their contacts to stop a shipment of 45 machine guns from reaching the streets of Miami.

The project cost about $400,000 altogether, with funding provided by the FBI, the Law Enforcement Assistance Administration and the Motion Picture Association of America, officials said.

In their nationwide travels the undercover agents visited and made deals with alleged pornography dealers in New York, Cleveland, Chicago, Las Vegas and Los Angeles.

Arrest warrants were issued for persons in several states, including Louis Guglielmi of Baltimore.

Until yesterday, the government's most significant case against a pornography distributor involved Michael Thevis of Atlanta, who was convicted of racketeering and conspiracy to murder a governemnt witness.

Those charged in the film-pirating case yesterday also face severe penalties under racketeering statutes. Most of those charged, however, face the less serious charge of interstate trafficking in "obscene, lewd, lascivious, and filthy films and magazines."

One federal prosecutor, speaking before the indictments were made public, said much minor charges "will make laughingstocks out of strike forces."