The D.C. City Council voted preliminary approval yesterday to a three-year extension of rent control, clearing the way for annual rent increases on about 180,000 house and apartment units.

The vote, after more than three hours of debate on proposed amendments, was 12 to 1. Only Council member Douglas E. Moore (D-at large) dissented.

As approved yesterday, the measure remained largely unchanged from the version agreed upon informally by Council members last week.

It will get its second reading and probable enactment by the Council on Nov. 29.

Under the complicated measure, which is spelled out in 89 pages of double-spaced typing, most tenants in the District probably would face rent increases generally varying from 2 to 10 per cent next year. Some raises probably would be steeper.

In 1979 and 1980, further rent rises would be linked to increases in the Labor Department's Consumer Price Index.

Before the Council met yesterday, more than 100 members of the Apartment and Office Building Association, the city's largest organization of landlords, assembled outside the District Building to demand "fair treatment."

They sought, among other things, an immediate rather than a delayed rent increase and expedited approval of increases in cases in which landlords claim economic hardship.

Because yesterday's meeting was a legislative session and not a hearing, spokesmen for the group were not able to present their demands directly to the Council. They were not even discussed.

In casting the lone vote against the measure, Moore - who is regarded as the front-runner for the City Council chairmanship in next year's election - accused his colleagues of being in the pockets of real estate interests. Wholesale rent increases will result, he asserted, in "pure and simple black removal."

Asked why he voted against the bill's passage, Moore said. "This is a landlord bill. The landlords have the vote.

Before the vote, the Council adopted only one amendment, by member David A. Clarke (D-one), that might effect the future level of rents. The amendment would require the city's Rental Accommodations Commission to consider - but not be bound by - the ratio of rental income to operating expenses in setting allowable charges to tenants.

Much of the discussions involved a multimillion-dollar rent-subsidy plan, included in the bill, to cushion the impact of the likely rent increases for low-income, elderly and disabled tenants. THe measure would authorize city payment of up to 15 per cent of rental costs.

Judith Rogers, special assistant to Mayor Walter E. Washington for legislation, warned the Council in a memorandum that the subsidy program "requires a substantial and continuing revenues source if it is to be effective."

Council member Marion Barry (D-at large) picked up that theme. He said it will take a long and time-consuming process before any money actually is appropriated for the subsidies.

Council member John A. Wilson (D-two) agreed. "Everybody's voting for concepts." Wilson said. "Concepts, hell, we'd better get some concrete . . . We'd better get into the politics of reality around here."

The city's three-year-old rent-control program already has been extended until Jan. 31 through emergency legislation enacted last month.

The new measure would permit The other is a provision that permits landlords to apply for "hardship" insetting a rent increasse next year.

One would be an automatic increase of 2 to 10 per cent, depending upon the level of services - such as utilitics - that landlords supply to tennants, other is a provision that permits lords to apply for "hardship" increases that could be greater.

John T. O'Neill, spokesman for the landlord group that demonstrated yesterday, said the provisions of the delays for rent increases that already are long overdue.