D.C. City Councilman Marion Barry, who in recent weeks has been campaigning for mayor in some of the most affluent areas of Washington, yesterday held a brief press tour at a partially occupied rundown apartment building.

During a 45-minute talk with several tenants in the building at 1420 R St. NW. Barry criticized one of the owners. Gregory S. Marsh, for allowing the 28-apartment, four-story building to deteriorate.

"What he is doing is trying to force everyone out of here so he can change it to a condominium," Barry said. The building borders an area undergoing rapid conversion of old apartment buildings to condominiums and house renovation.

Reached by telephone, Marsh, who is listed as president of 1420 R St. Inc. accused Barry of using tenants as a "tool" to get press coverage.

Several tenants said the building has been deteriorating rapidly since Marsh bought it last October. They said they had no heat last winter, have not had hot water since April and were without electricity in the hallways and in several apartments a number of times the past five months.

Two inspectors from the city's housing code enforcement office were at the building yesterday just before Barry's 3 p.m. tour began. They said they had oil delivered to the building that day and had electrical repairs made.

Thomas Butler, chief of the city's housing inspection, said costs of the oil and repair work would be passed on to Marsh on his property tax bill.

John Hampton, director of client serivces of the rental accommodation office, said the building has 620 housing code violations and has been cited five times in recent months for fire hazard violations.

Julia Boyd, who said she has lived in the building since 1975, showed Barry where a large section of plaster had fallen from her living room ceiling leaving gray wooden boards exposed. The plumbing for the bathroom sink of her two-bedroom apartment, which she shares with her husband and their four children, was removed by repairmen in April and not replaced she said.

"Before (Marsh) bought this building it was kept clean and you couldn't even smell the trash room," Boyd said. "Now we're moving. We just can't stand to stay here any longer," she added.

"There are many buildings like this in the city," said Barry, "but the present administrations of (housing development director Lorenzo) Jacobs and (acting Corporation Counsel Louis) Robbins have been insensitive to low-income people."

Jacobs could not be reached for comment yesterday, but Abraham Greenstein, deputy administrator of neighborhood improvement, said his office routinely forwards landlord housing code violation cases to the corporation counsel for prosecution.

Robbins responded that "when we get a (housing violation) case, we prepare them and prosecute them" but added he did not know the particulars of the Marsh case. Assistant Corporation Counsel) Mark Mann, who declined to discuss particulars, said housing violations involving 1420 R St. NW "are pending prosecution."

Marsh said yesterday he has sent workmen to the building to make repairs but "the hooligans who live in there" threatened them and they refused to return.

Marsh also said he talked to Barry two months ago at a campaign luncheon held by businessmen. "I think he is a very good candidate (for mayor) and he seemed to be very much in compliance with (landlords') problems.

"(Barry) said he was in favor of trying to provide incentives to landlords" by relaxing rent control regulations, Marsh added. "What he told me sounded good."