Faculty members at the University of the District of Columbia were paid the highest average salaries and fringe benefits in the Washington area last year and among the highest in the country, according to a report by the American Association of University Professors.

Full professors at the new university, which is operated by the city government, averaged $35,700, AAUP said, including salary of $28,800 and medical, pension, and other fringe benefits that cost $6,900.

Only one other local university, Georgetown, paid a slightly higher average salary to its full professors, $29,900. But because of fringe benefits, total compensation for professors was $1,400 higher at UDC.

In the other faculty ranks - from associate professor down to instructor - both average salaries and fringe benefits at UDC were the highest in the area.

The university was also in the top 5 percent nationwide among the approximately 1,900 institutions included in the AAUP survey.

On the other hand, salaries and fringe benefits at the University of Maryland where just about at the national average. Pay at the University of Virginia was relatively high for top professors but low for lesser-ranking faculty members.

Among local universities, average pay was lowest in most categories at Catholic University and George Mason. American University and the University of Maryland were in the second lowest group. Pay at Georgetown, Howard and George Washington was relatively high but below the averages for UDC.

AAUP officials noted that in the early 1970s pay was just slightly above average at Federal City College, D.C. Teachers College, and Washington Technical Institute - the three public colleges that merged last year to form UDC.

In recent years pay raises and fringe benefits improvements at the public colleges here were tied to those for other D.C. government employes. The gains considerably outpaced those at most other universities.

"There's been no extraordinary action by anybody to increase (UDC) salaries," said Ronald H. Brown, chairman of the university trustees. "Every time salaries in the District government go up, our folks get the same increase, and District salaries are tied to the federal government . . . City police, firemen, and teachers also get higher salaries now (than elsewhere in the area)."

UDC public information director John Britton added that average faculty pay is high partly because "very few people leave. People have been here for years and they move up the steps of the pay scale."

Britton noted that salaries are relatively high at other big city public colleges, such as those in New York and New Jersey, where the cost of living is relatively expensive.

"As the cost of living has gone up, we've gotten some of it back (in pay raises)," Britton said.

Last year the cost of living in the Washington area went up 6.8 percent, according to Labor Department figures. Salary increases for UDC faculty, including longevity pay as well as higher pay scale, ranged from 7.1 percent for associate professors to 12.1 percent for full professors, AAUP said.

The average pay for UDC instructors, who are at the bottom of the academic totem pole, was $18,900, including $15,800 in salary and fringes worth $3,100.

At Georgetown and Howard, universities both second in this category locally, instructors averaged $16,000 last year. At Catholic University and the University of Maryland they averaged just $14,200.

Throughout the country, AAUP said, pay generally is highest for full professors, associates and assistants at major universities that grant doctorate degrees. It is highest for instructors at two-year community colleges.

University of the District of Columbia pay is relatively high in all categories. Compared to Yale, for example, UDC pay is $1,400 less than the average for full professors, but $3,900 above Yale for associate professors, $5,200 more for assistant professors and $4,900 more for instructors.

At a hearing yesterday Sen. Patrick Leahy (D-Vt.), chairman of the Senate District Appropriations subcommittee, said Congress, wants to support the academic program at the city university, but he again expressed doubt about the need for a new $56 million downtown campus just north of Mount Vernon Square.

University president Lisle C. Carter Jr. noted that plans for the new campus have already been approved by the D.C. government and House District Appropriations subcommittee.