A special federal grand jury concluded last week that there was insufficient evidence to support allegations that White House chief of staff Hamilton Jordan used cocaine.

In a 53-page report made public yesterday, the special federal prosecutor assigned to the case, Arthur H. Christy, said the grand jury voted unanimously not to bring any criminal charges against President Carter's top aide.

The investigation, started six months ago after a preliminary inquiry by the FBI, dealt with claims that Jordan had sniffed cocaine on a 1978 visit to New York's Studio 54 nightclub and on a 1977 trip to California.

The special prosecutor said two of Jordan's accusers in the New York case -- Studio 54 owener Steve Rubell and a New York drug dealer named John (Johnny C) Conaghan -- gave vague, shifting accounts of what happened. jChristy voiced doubts about the "overall credibility" of the third key witness, New York publicist Barry Landau.

The report indicated that Rubell and Conaghan had been taking drugs themselves on the night in question.

Christy also said "there is no evidence whatsoever" that Jordan used cocaine on an Oct. 21-22, 1977, visit to California. One witness reported seeing Jordan at the end of one party there "with a slightly glazed look, a runny nose and a white substance across his upper lip," but, Christy said, "he could not identify the white substance as cocaine or any other drug." s

At the White House, both President Carter and Jordan expressed gratification at the outcome of the prolonged controversy in separate statements.

"My confidence in Hamilton Jordan's integrity has never wavered," Carter said.

Jordan pointed out that he had denied the charges from the outset and said he had cooperated fully in the investigation.

"I have always respected the law and our system of justice," he said."The outcome today has vindicated my faith."

According to The Los Angeles Times, after Jordan was informed of the results of the inquiry, his staff broke out two bottles of champagne for an impromptu celebration in Jordan's spacious corner office down the hall from the White House Oval Office.

According to a White House official Carter dropped by, shook hands and congratulated his top aide.

Christy submitted his report to the three-judge federal court that appointed him Nov. 29 under the provisions of the Ethics in Government Act. A secret addendum, including grand jury testimony supporting the findings, was forwarded to Attorney General Benjamin R. Civiletti at Christy's request.

The special prosecutor said he and his staff conducted about 100 interviews of 65 people. Thirty-three witnesses were called before the grand jury, which began meeting in March and held 19 sessions before closing down the investigation May 21.

The report pointed out that the allegations against Jordan arose last August in the midst of efforts by Rubell and another Studio 5 owner, Ian Schrager, to get the Justice Department to drop or at least reduce tax-evasion charges against them. Their lawyers first indicated they had information about the use of drugs "by a high government official" and then told prosecutors in New York Aug. 22 that the individual was Jordan.

The story came from Rubell, supplemented by a secret tape recording he made of an Aug. 17 conversation with "Johnny C" in Schrager's presence. In it, the drug dealer told Rubell at one point:

"I gave Hamilton two toots and you toots [sic] and I left . . . I was down there maybe two minutes with him . . . I don't know what happened before, but you said come downstairs and turn a friend on. And all I did was turn him on, two toots, gave you maybe one and I left."

Under questioning by the FBI, however, Conaghan later said he had been told that Rubell was angry with him and, on being summoned to his office "agreed with Rubell's recollection of the incident to avoid being argumentative."

Conaghan said on the American Broadcasting Co. "20/20" program in October that he administered cocaine in Studio 54's cluttered basement to a man later identified to him as Jordan, but excerpts of the interview, which were not broadcast, showed him stating that he had "a reasonable doubt" that it was really the White House aide.

The smalltime drug dealer, who is awaiting sentencing on unrelated drug charges, later acknowledged to Christy's office that he had taken cocaine that evening and also that he had had a few shots of "good old Russian vodka," defining a shot as containing six to eight ounces each. He said he had given cocaine to a man at Studio 54 at Rubell's behest, but described him as considerably taller than Jordan. Conaghan was not even sure that the incident took place the night Jordan had been at Studio 54, Christy noted.

As for Rubell, the report said he had publicly stated Jordan "took a hit in each nostril," but later told investigators he said that "only because that is what he recalled Johnny C had told him."

The report described Rubell as a frequent user of Quaaludes and an occasion user of cocaine." Christy said Rubell "assumes that he used drugs that evening," June 27, 1978, himself.

Landau, a frequent patron of Studio 54, told investigators he was first asked about Jordan's visit by Rubell on the night of Aug. 27, 1979. Landau said he was unaware the charges had already leaked to the press and told Rubell "that he did not recall Mr. Jordan being at Studio 54."

The next day, the publicist told one of Rubell's lawyers that he had seen Jordan at the nightclub after all and that Jordan asked him "if he could obtain some cocaine."

Christy said it was possible Landau had talked to Jordan that evening and asked the White House aid for a favor, but Christy dismissed the rest of his account. The special prosecutor noted that all six people with Jordan, including two women identified only last month, denied hearing Jordan ask for cocaine in their presence. Landau had said some members of the Jordan party were within earshot.

Voicing doubts about landau's overall credibility, Christy said in a footnote that the publicist had pleaded guilty in 1977 to making a false statement on a passport application.

Turning to the California investigation, which was apparently more limited, Christy said there was no evidence Jordan had taken cocaine at either a Beverly Hills nightclub on Oct. 21, 1977, or at a party the next night at the home of Los Angeles businessman Leopold S. Wyler.

The report said there was some evidence drugs were available at the Wyler home. Wyler told of being offered "a hit" the night by someone he could not identify, and an 18-year-old UCLA student, Cynthia Alksne, said a man she did not recognize offered what she took to be cocaine by putting the knuckle of his right index finger under his nostril and making a sniffing sound. But Alksne never saw any cocaine at the party, the report noted.

Another witness, Andrew Cohen, 19, who served as a volunteer chauffeur for the party, told investigators he was offered marijuana and cocaine at the Wyler party, but not by Jordan or anyone with him. He said he saw Jordan with "a white substance" on his lip, but could not say what it was.

Christy pointed out that Cohen was also emphatic about having driven White House press secretary Jody Powell to and from the party. The special prosecutor said Powell did not go.