Despite the official outcry over publication of renegade CIA officer Frank Snepp's unauthorized account of the fall of Vietnam, Jusitce Department and Senate Intelligence Committee sources believe there is little likelihood of either federal legal action against or a full-scale investigation into his allegations.

Snepp, the 34-year-old former intelligence analyst for the Central Intelligence Agency in Vietnam, spent two days last week in staff interviews and more than three hours testifying in a closed session Wednesday before the Intelligence Committee. Informed sources said the question in of Snepp by the committee was often sharp and after the conclusion of the session there was little inclination on the part of the senators ot pursue a full investigation.

"We do not want to fight the war all over again," said a committee source.

The committee also reached the conclusion according to one source, that there is little in snepp's book "Deent Interval" that could be construed to violate the CIA's intelligence sources or methods.

In interviews Snepp has said he attempted not to reveal the names of clandestine officers mentioned in the book. As for the oath that requires all CIA employees to let the agency have prior review of their published material, Snepp has said he decided to break it only after a senior CIA offical leaked his own version of the end to the war to the press.

While a former CIA review committee is still going over Snepp's book line by line looking for possible security breaches, the Senate committee's decision signals the probability that no federal legal action will be taken against by the Justice Department.

On Nov. 25 CIA Director Stansfield Turner requested that the Justice Department look into the possibility of initiating legal action against the former CIA officer.

However, Justice officials familiar with the Snepp matter said last week that a federal court ruling on an earlier unauthorized book the CIA essentially narrowed their jurisdiction to matters of violations of official classified material.

That decision, by the Fourth U.S. Circuit Court of Appeals in 1972, was made on a book by former CIA officer Victor L. Marchetti and John Marks. The court ruled that Marchetti, who had taken the prio-review oath, was bound by it after CIA attorneys enjoined publication of his book. The intelligence agency was allowed to make 162 deletions in the book.

Snepp's publisher, Random House, went to great trouble to cloak the Vietnam book in secrecy in order to ensure its publication before the CIA could obtain an injunction against it similar to the one obtained in the case of the Marchetti-Marks book.

A CIA spokesman noted last week that since Snepp was no longer employed by the agency sanctions under the prior-review oath - that is firing or demotion - no longer applied.

"Turner went to the Justice Department," the spokesman said, "because this just seemed to be the last straw and he wanted some way to put a stop to these books which violated the oath." Turner has spoken out sharply against former intelligence agents who have published without clearance from the agency and, like former CIA Directors George Bush and William E. Colby, has sought to rally congresinally support for legislation to employ criminal sanctions against ex-employees who violate the oath.

Turner also testified before the Senate Intelligence Committee last week during a close-door session, and sources said he touched on the need for stricter legal sanctions against unauthorized publications by current or former CIA employees.

The issue is a particulary touchy one at this time since the CIA is conducting a highly controversial manpowre outback of more than 800 of its clandestine branch members. The cutback has generated considerable emotion among many CIA employees, including threats by some to publish once they are fired.

Since Turner's request for a Justice Department review of the Snepp matter, Justice attorneys have had several informal sessions on what to do, including one over breakfast recently with Attorney General Griffin B. Bell.

"It's really a terrible case," said one Justice official. "We can't really win no matter what we do."

If the major purpose in initiating legal action against Snepp is to deter other similarly unauthorized books and articles, the Justice official said, a failure to show that the Snepp book disclosed classified material could backfire.

"Even if a court ruled in our favor it would be hard to show damages if no classification was violated," the official said. "If the court awards $1 in damages, is that any deterrent?"

Justice officials also fear that a court suit against Snepp might be likely to draw widespread publicity and subsequently boost the book's sales.

There is one recent case, involving publication of an unauthorized book by ex-CIA agent Joseph Smith entitled "Portrait of a Cold Warrior," that was deliberately ignored by the CIA for just that reason, according to an agency oficial.

On the other hand, federal legal officials said they are aware that by looking the other way on the highly publicized Snepp book they could open themselves to a flood of similar ventures. "You can't decline too many cases like this," said one official, "or people will see you don't mean what you say about a contract."