The Department of Housing and Urban Development, after an extensive investigation, found that Alexandria officials did not purposefully reduce housing opportunities for blacks as was alleged in a complaint filed against them, according to a report released yesterday.

But while absolving the city of the discrimination complaint, HUD officials have charged the city with violating federal housing regulations by failing to keep required racial data.

A black group, the 16th Census Tract Crisis Committee, filed a complaint with HUD last July saying that by such actions as relocating Rte. 1 through a black neighborhood and declaring the predominantly black Parker-Gray neighborhood a special preservation district, city officials violated blacks' constitutional rights to fair housing opportunities.

City Manager Vola Lawson, who was housing director from 1980 to 1985, denied the charge that the city failed to record the race of people benefiting from federally funded projects.

"The comment that there are no racial data is inaccurate," Lawson said, in an unscheduled news conference last night. "Racial data has always been kept for CDBG Community Development Block Grant or federal programs."

Lawson called the HUD response, which she received Monday in a letter, "somewhat baffling." She said she would immediately request a meeting with HUD officials.

John J. Kane, HUD's director of the Philadelphia Office of Fair Housing and Equal Opportunity, which dispatched the investigative team to Alexandria, said yesterday he could not comment on the letter his office sent.

"We have had a fairly extensive review and spent a lot of staff time," Kane said. "Now we are at the point in time where they [the city and the 16th Census Tract Crisis Committee] will get back to us and react."

Within two weeks, Kane said he hoped to have heard from both parties and release a list of "recommendations" to the city.

Euroda Lyles, spokesman for the 16th Census Tract group, declined to comment on HUD's finding.

Lawson and Mayor James P. Moran Jr. were irked yesterday at how the investigation was handled and how much it cost the city.

Lawson said the city spends "several thousands of dollars," in staff time complying with the demands of HUD officials.

"I'm still annoyed that we had to spend as much time and effort in defending ourselves for something that we should not have been accused of in the first place," Moran said. He said he has asked the staff to assess the actual cost of the investigation.

"The city has an outstanding record in housing," Lawson said. "It has tripled its [federally] assisted housing in the last decade and the majority has gone to minorities."

According to the HUD report, 58 percent of all properties purchased through the Homeownership Assistance Program were purchased by blacks, and 63 percent of the total number of persons who sought housing counseling were black.

But it said the lack of documentation on other housing programs made it difficult to assess their benefit to blacks. Still, the report said, " . . . it does not appear that discriminatory treatment was a factor in the administration of the program."