The reputed leaders of New York City's five organized crime families have been indicted by a federal grand jury on charges that they participated in a nationwide "commission" of 26 Mafia families that controlled "mob" activities ranging from murders and drug trafficking to loan sharking, gambling and labor racketeering.

It was the most dramatic move yet in a state and federal war on the mob that, since August 1983, has resulted in indictments of more than 300 alleged New York Mafia members and associates.

"This is a bad day, probably the worst ever, for the Mafia," U.S. Attorney Rudolph Giuliani said in New York yesterday. No federal indictment ever charged so many bosses, he said.

FBI Director William H. Webster called the indictment "historic" and said it "exposes the structure and leadership of organized crime on a scale never done before."

A 15-count indictment, announced by Giuliani, charges nine reputed leaders of the Genovese, Gambino, Lucchese, Colombo and Bonanno organized crime families with regulating and dividing up Mafia activities, including a multimillion-dollar extortion scheme, code-named "the Club," that the Mafia allegedly used to control the cement industry.

The indictments also charge that the commission authorized at least five murders, including the slayings of Carmine Galante, then boss of the Bonanno family, and three Bonanno family captains: Alphonse (Sonny Red) Indelicato, Dominic (Trin) Trinchera and Philip (Philly Lucky) Giaccone.

Those indicted include reputed bosses Anthony (Fat Tony) Salerno of the Genovese family, Paul (Big Paul) Castellano of the Gambino family, Anthony (Tony Ducks) Corallo of the Lucchese family, Philip (Rusty) Rastelli of the Bonanno family and Gennaro (Gerry Lang) Langella of the Colombo family.

The others indicted were identified as Salvatore (Tom Mix) Santoro, reputed underboss or second in command of the Lucchese family; Christopher (Christie Tick) Furnari, the reputed consiglieri or counsel of the Lucchese family; Ralph Scopo, a member of the Colombo family and president of the Concrete Workers District Council of the Laborers International Union of North America; and Aniello (Neal the Lamb) Dellacroce, reputed underboss of the Gambino family.

Dellacroce's name came up last year in connection with real estate dealings by John A. Zaccaro, the husband of former Democratic vice-presidential nominee Geraldine A. Ferraro. Zacarro and Ferraro denied any impropriety in the dealings.

All nine defendants were arrested in a sweep Monday night.

The indictments, based on a federal anti-racketeering statute, followed a 19-month cooperative probe -- including federal, state and local investigators -- that began with an investigation by the New York State Organized Crime Task Force. The task force went to federal authorities because there is no anti-racketeering statute in New York.

Because of the large number of investigative agencies involved in the operation, numerous leaks preceded the indictments, and references to the investigation had appeared recently in New York newspapers, on network television news and in Time magazine.

Investigators in the case had planted a bugging device behind the dashboard of a 1982 Jaguar driven by Corallo's chauffeur, allowing them to trace Corallo to a "sit-down" of family bosses and to hear him later discussing the meeting, according to law enforcement officials.

The commission was formed in 1931 by Charles (Lucky) Luciano and other New York crime figures to coordinate operations of the five crime families that had flourished since the turn of the century, the indictment charged. One of its principal duties was to resolve leadership disputes among various factions.

One such dispute allegedly was settled in 1979 when the commission authorized the murder of Galante, who led a faction in the Bonanno family. He was gunned down in a Brooklyn restaurant, his cigar still clenched between his teeth.

Webster, who appeared at a news conference with Giuliani, said the indictments were the culmination of a Reagan administration crackdown on organized crime that has gone on for about three years. Last year, Webster said, there were 3,118 indictments and 2,494 convictions of organized crime figures in the United States. In 1983, he said, there were 2,405 indictments and 1,331 convictions.

"Never have I seen the law enforcement community better mobilized to deal with the toughest criminal enterprises . . . ," Webster said. "All the things that help to undo our society are now confronted square on in this indictment. We are now taking out the top players. The ruling body of the most powerful organized crime elements in the U.S. . . . has now been brought to the bar of justice."

The federal war on the New York Mafia began more than three years ago, when more than 100 federal agents and city police detectives were divided into five groups, one to investigate each family.

Last week, a Brooklyn-based federal organized crime strike force headed by Edward McDonald brought indictments against Santoro and two officers of a Mafia-dominated Teamsters union local charging that the three had extorted more than $246,000 from companies handling air freight at John F. Kennedy Airport.

Giuliani said that "thousands of hours of tapes" not yet made public are expected to provide more evidence for cases "that can aid in our breaking up of the mob."

In addition, Giuliani said, investigators were able to crack the top leadership of the mob with the help of about 30 witnesses who broke the Mafia's strict code of silence.

Steven S. Trott, assistant attorney general in charge of the criminal division, urged victims of organized crime to step forward and give information to the authorities.

"The mob is on the run, and we will simply ask you to come forward," he said. "Now is the time . . . . This case that is being brought today truly represents the bull's eye. It's our expectation that this indictment will operate as a javelin to drive deeply into the heart of organized crime."

In addition to the racketeering conspiracy charge, all the defendants except Rastelli are named in the 10 extortion and three labor bribery counts. Racketeering carries a maximum penalty of 20 years in prison.

Each extortion count also carries a maximum penalty of 20 years and each labor payoff charge, a maximum one-year sentence.