The Board of Education for the Roman Catholic Archdiocese of Washington announced yesterday that it has approved a plan to merge four inner city high schools into one central facility in Northeast Washington by 1981.

The merger, subject to final approval from Cardinal William W. Baum, was criticized by black Catholics who said the plan signaled a lack of commitment to educating the city's poor and middle class students. Enrollment at the four schools is predominantly black.

The archdiocese contended that the consolidation -- which would affect about 700 students and close three schools -- is necessary because of increasing costs and declining parochial school enrollment.

The Secretarist for Black Catholics, an archdiocesan agency which had strongly objected to the proposal, argued that the emphasis on finances overshadowed the impact on the inner city when schools are shut down.

Secretariat members were scheduled to meet last night to discuss the board's approval of the plan, which has been under discussion for the past three months. The secretariat's executive director, Jacqueline Wilson, refused to comment on the decision yesterday.

In a 9-to-5 vote Tuesday night, the school board recommended that three girls high schools be closed and that students be transferred to St. Anthony's High School, at 1001 Lawrence St. NE, which will be expanded to accommodate about 850 students.

The schools proposed for closing are St. Cecilia's Academy, 601 East Capitol St.; Immaculate Conception Academy, 24th and K streets NW, and St. Patrick's Academy, 924 G St. NW.

Archdiocesan School Superintendent Leonard DeFiore said yesterday that consolidation of the schools -- where enrollment is low and operating costs are high -- will keep the cost of tuition down and allow for broader educational opportunities.

"What we're doing is relocating the site of Catholic education into a modern plant," DeFiore said in a telephone interview.

DeFiore said that under the terms of the plan, two wings will be added to St. Anthony's School to make room for the additional students at a projected cost of $2 million to $3 million. Construction is expected to be funded from the sale of Immaculate Conception and St. Cecilia's Schools, deFiore said, although the final decision on funding is up to Cardinal Baum.

According to DeFiore, the school properties each have an assessed value of $1.5 million.

If the merger is approved by Cardinal Baum, school authorities will evaluate individual curriculums at the four schools and then draw up a combined educational program for the consolidated school, DeFiore said.

DeFiore said he expects the curriculum at St. Anthony's would include remedial and career education courses -- like business and computer skills -- as well as college proparatory and honors classes.

About 250 girls now attend the three schools that are scheduled to close, school officials said. DeFire said that if the merger is approved the 100 boys who now attend St. Anthony's School, where total enrollment is about 250, will have guaranteed admission to either Mackin or Carroll high schools, both run by the archdiocese.

Immaculate Conception Academy established in 1865 and the city's oldest girls' school, and St. Cecilia's Academy, both concentrate on college preparatory courses and offer remedial classes, DeFiore said. St. Patrick's curriculum focuses on business skills, he said.

"Of course we would like to keep our own school," said Sister Kathleen Reilly, principal at St. Cecelia's, "But I think we all realize that we couldn't keep all four schools open."

The school board "told the staff there would be a job available [at St. Anthony's] for everyone on the staff. And they invited any of the sisters to go, too," Sister Kathleen said.