A female career employe of the Central Intelligence Agency's supersecret cover operations branch has sued the spy agency, claiming it systematically discriminates against women seeking undercover assignments, often for frivolous reasons.

Bernice Turbeville of Fairfax County charged in a sex discrimination lawsuit that her superiors throttled her advancement by criticizing her "potted plants" as possible security hazards and complaining that she snacked in the morning on coffee and danish.

The suit, filed in U.S. District court in Washington on behalf of Turbeville and and about 500 women employed by the agency's covert operations section, alleges a male supervisor also suspected Turbeville of once taking part in a "bitching session" and of participating in a feminine protest march in the District of Columbia on a day when she had claimed sick leave. Both suspicions were false, the suit says.

The CIA, which was named as a defendant along with its director, William J. Casey, yesterday declined to comment on the allegations. Agency spokesman Dale Peterson said copies of the suit had not yet been received at CIA Headquarters in McLean.

Turbeville, who lives in Chantilly, alleged in her suit that she routinely was denied promotions and pay equal to those granted to male agents of the same ability. She also failed to receive specialized training and overseas assignments except for a stint from 1959 to 1961 when she served as "Chief of Records," a file room duty at an unspecified location, the suit claims.

Such treatment is typical of that received by the 500 women who have worked in covert operations for the CIA from September 1974 to the present, the suit contends.

Turbeville, now an operations officer with a GS-12 rating, said in the suit that she joined the War Department's Strategic Services Unit as a clerk in May 1946 and movedto the CIA at its inception in 1948.

Despite early promotions and strong fitness reports that enabled Turbeville to become a GS-9 intelligence analyst by 1953, the suit says, her career later slowed. She served more than 11 years as a GS-9 operations officer, five years as a GS-10, and then nearly nine years as a GS-11 before being promoted to her current rating.

"This pattern of lengthly years of service prior to obtaining promotions does not comport with the pattern for similarly situated males in the [Directorate of Operations]," the suit contends. She alleged that her security record has been good, but said that one supervisor claimed, for reasons that were not explained in the suit, her potted plants were a possible security risks.

Turbeville alleges she has been unsuccessful for the past two decades in attempts to obtain special training and overseas assignments, although such opportunities are regularly given to male agents and are "intergral to career advancement and upward mobility" at the agency.

Written criticisms by male superiors about Turbeville's job performance followed an Equal Employment Opportunity complaint she filed with the agency in September 1974, she alleged. The CIA denied her claim three years later and the ruling has been appealed.

In her suit Turbeville seeks double the back pay she contends she has been denied by the agency's allegedly discriminatory practices since 1974. Her lawyer, John Grad of Alexandria, said yesterday he was uncertain of the dollar amount involved.

The suit also asks that Turbeville be promoted to a higher grade and that the court impose an affirmative action hiring plan on the agency's covert operations branch.