Government proposals to reduce mental health benefits for an estimated 96,000 federal employes and their dependents have caused an angry stir among Washington-area psychiatrists and their patients, who argue the cutbacks would discriminate against a class of health-care receivers and have repercussions in the mental health field as a whole.

The Office of Personnel Management has been in secret negotiations with several health-care insurers for months. But it is the agency's private talks with Blue Cross/Blue Shield, the largest provider of health-insurance coverage for government workers, that are arousing concern in the psychiatric community.

The psychiatrists say they have heard from Blue Cross/Blue Shield and OPM sources that the two parties are about to sign off on a plan that would limit outpatient therapy visits to 50 a year and require patients to pay 50 percent of the cost per visit, an out-of-pocket increase of 67 percent over what they now pay and 133 percent over what they paid in 1979.

Assuming a standard therapy visit of $60, this would mean the Blue Cross/Blue Shield plan would pay only $30 of the patient's bill compared to $42 it pays now, under a 70/30 arrangement, and the $48 it paid two years ago when the plan paid 80 percent of the cost.

Health benefits for hospitalized mentally ill patients, many of whom are juveniles, would be even more severely curtailed, according to psychiatrists, who say they have learned that coverage will be limited to 60 days a year. The reductions, they said, would also have a disproportionate impact on all patients receiving intensive analysis.

Neither OPM nor Blue Cross/Blue Shield, prohibited by law from discussing the negotiations, would talk about the health-care proposal except to say its details are still being worked out.

Blue Cross/Blue Shield provides health insurance for about 51 percent of the total federal work force, including about 746,000 area employes and their family members. Nationally, the insurance firm estimates that more than 96,000 federal workers and their dependents claimed benefits for emotional and mental health treatment in 1980, including more than 20,000 in the Washington area. An employe's share of the premium costs here for high option, family coverage is now about $60 a month.

The outcry from psychiatrists and patients has put both OPM and the health-insurance provider on the defensive, particularly since the psychiatrists are warning that the cuts could ultimately affect psychiatric benefits for the military and private employes.

"If we tried to provide the same level of benefits in 1982 as we do now, it would cost the government another half-billion dollars, and this is not exactly the year to go over to the White House and ask for that," said OPM spokesman Pat Korten.

Korten said health-care benefits for its workers cost the government $2.25 billion this year, the total paid out under 120 plans in the Federal Employe Health Benefits Program. The government, he noted, contributes an average of two-thirds toward the premium costs of the various plans, compared to the full premium costs usually assumed by private-sector employers.

OPM, in court over its attempts to eliminate abortion coverage for federal workers, is trying to trim health-benefit costs, said Korten, who denies the agency is singling out psychiatric care. He said the actual proposal to cut mental health benefits came from Blue Cross/Blue Shield when all the health plans were sent back to the drawing board.

But Jim Hook, director of technical services for Blue Cross/Blue Shield, said both parties will sign the coverage contract when it is ready and both parties have a say on its contents.

"It's a negotiation," he said, "and any particular benefits you want to talk about are wide open."

Right now, however, the psychiatrists and their patients -- aided by support from the American Medical Association -- are doing almost all the public talking.

"We think the decision is arbitrary, capricious and discriminatory," said Dr. Melvin Sabshin, medical director of the American Psychiatric Association, who charged yesterday that the secrecy surrounding the decision-making has denied the psychiatric community a chance to express its concerns.

Noting that health plans continue to pick up 80 percent of the cost of other health-care treatments, Sabshin suggested that "if OPM and the insurance carriers need to reduce benefits, why do they single out one group? Why don't they look at other benefits, too?"

Dr. Harold Eist, president of the Washington Psychiatric Society, said cuts would be "devastating to patients."

But he conceded as well the economic impact the cuts would have on psychiatrists. Blue Cross/Blue Shield provides about one-third of all psychiatric insurance for the region.

"The battle the psychiatric society is generating is primarily for the patients, but physicians would be suicidal if they didn't have enlightened self-interest," Eist said.

Last June, during congressional hearings on government health-care benefits, Rep. Michael D. Barnes (D-Md.) said that lower grade federal employes would be hurt the worst by cuts in mental-health benefits. He said 26 percent of those receiving mental-health care in the area are below the GS 9 level.

But more affluent federal workers and their families, including a father who has spent $20,000 of his own money on hospitalization for two sons, said in interviews they might lose or have to curtail treatment if health benefits are cut.