Aladena (Jimmy the Weasel) Fratianno, the admitted Mafia hit man who has spent most of the last decade as a government informant, is losing his government subsidy of about $100,000 a year, the Justice Department said yesterday.

Fratianno, who joined the federal witness protection program in 1978, will continue to receive protection from the U.S. Marshals Service when needed, but his allowance for living expenses will be cut off, department spokesman John Russell said. Starting today, Fratianno will be expected to support himself.

"He's very upset," Russell said. "He has given invaluable service to the government and law enforcement officials, but everyone is terminated from the program sooner or later."

Fratianno joined the federal program in 1978 after learning that the Los Angeles organized crime family had put out a contract on his life and that federal prosecutors were preparing multicount indictments against him. Since then, the Justice Department has spent $951,326 supporting him, his wife and daughter, Russell said.

"Mr. Fratianno, in our judgment, is able to take care of himself," Russell said. He said the 74-year-old Fratianno is eligible for social security benefits and receives royalties from two books about his life. The most recent, "Vengeance Is Mine," is being published this summer, with Fratianno entitled to a third of the profits.

In addition, Fratianno, who was a professional hit man and a top mob boss in California before he turned government informer, has investment interests in two houses and a condominium, Russell said.

Under the witness protection program, Fratianno has been given a new name, a new identity and has been settled in an undisclosed location.

He could not be reached for comment, but in a call Wednesday to the States News Service here, Fratianno said, "I'm a dead man.

"They just threw me out on the {expletive} street. I put 30 guys away, six of them bosses, and now the whole world's looking for me. They just get finished using you and they throw you out on the street," he said. "I'm 74 years old. Where am I going to work at my age? I'd have to go where I know people. I'm facing a very dangerous situation."

Fratianno has been one of the government's most reliable organized crime informants. His testimony helped convict several mob bosses, including Frank (Funzi) Tieri, former head of the Genovese crime family; Carmine (Junior) Persico, former boss of the Columbo family; Joey Aiuppa, former head of the Chicago mob; and Dominic Brooklier, former boss of the Los Angeles family.

His most recent court appearance was last year in New York, at the trial of Anthony (Fat Tony) Salerno and 12 other reputed mobsters.

Russell said Fratianno probably has been subsidized "longer than any other individual under the program."

Fratianno's case has been under review since 1983, Russell said, and the government has already given him extensions. "It's a witness-protection program. It's not designed to reward people . . . . He's very upset, but there's nothing else we can do."

Under the program, witnesses who are relocated with a new identity receive living expenses from the government for a time, but are expected to find jobs and support themselves.

In the new book, Fratianno makes it clear that the Justice Department never promised a lifetime subsidy.

He quotes Gerald Shur, head of the witness program, saying, "We're not offering you a glamorous life, and probably nothing compared to what you're used to. The only thing we're guaranteeing is to keep you alive on our terms. And that means we'll take care of you and your family. We'll choose a place to relocate you, feed you, and cover your basic needs, like housing and medical, until you start making a living."

The department said about 5,000 witnesses have been protected under the program since it was started in 1970. There are currently about 300 in the program, half of them in prison.