A U.S. appeals court here yesterday sharply limited the instances in which federal officials can be charged with accepting bribes.

The ruling said it is not sufficient in a criminal bribery case just to show that a federal official used his office for personal gain. Instead, the court said, prosecutors must also prove the official was in a position to directly influence decisions in return for the favors.

The ruling by the U.S. Court of Appeals reversed six to eight bribery related charges against a former high ranking labor adviser at the U.S. Department of Housing and Urban Development.

Charles T. (Red) Muntain was assistant to the secretary for labor relations at HUD until he retired in 1977. He was a consultant to the HUD secretary, the secretary's principal labor relations policy adviser, the chief HUD spokesman on labor relations and the chief liaison between HUD and organized labor.

The government's case against Muntain concerned his involvement while he was at HUD in a private scheme to sell group automobile insurance to labor unions as a negotiated benefit in union contracts.

He had a partnership arrangement with other persons in the scheme and introduced those persons to labor union officials he met through his HUD job, the court noted.

In return, Muntain received small payments for expenses and a trip to Ireland, the government charged. According to the prosecution theory, Muntain had been bribed.

The appellate court disagreed yesterday."Muntain's use of his official position to promote a purely private venture created an appearance of impropriety, his conduct is reprehensible, but it is not criminal . . .," the court ruled.

The appellate court said there was no evidence that automobile insurance as a benefit for labor unions fell within HUD's jurisdiction, so therefore Muntain could not have performed any "official acts" that would have aided the insurance scheme.

The court accused the government of trying to broaden the term "official act" to include such public duties including in this case, general meetings with labor union officials.

"In essence, the government would have this court construe (bribery law) as a statutory prohibition against the misuse of public office and contacts gained through that office to promote private ends," the court said.

"To construe that statute in the manner advocated by the government is, we think, to extend its language beyond permissible bounds, "the court added.

It said there was no evidence Muntain's meetings with labor union officials concerning the insurance plan involved any subject that could come before him as a HUD official. Thus, it said, he could not be improperly influenced by any payments he received.

The government had argued that as a part of the scheme, Muntain ordered subordinates at HUD to help promote the plan. The appellate court said the order to subordinates to meet with the labor union officials still was not an "official act" by Muntain because the issue of insurance as benefit for labor unions was not a topic he would ever confront at HUD.

Prosecutors who have handled bribery and other white-collar criminal cases in the past expressed concern about the ruling and said they would consider appealing it. Muntain's attorney, Plato Cacheris, could not be reached for comment late yesterday afternoon.

The court upheld Muntain's convictions on two counts of failing to inform HUD about his outside partnership arrangement in the insurance scheme. He was sentenced to five years' probation and told to serve 100 hours of community service beginning at the end of his trial.