Angry District of Columbia tenant groups yesterday launched a late but intensive lobbying campaign to try to get the City Council to delete a provision of the pending rent control bill that would allow landlords to impose rent increases of up to 10 percent every time an apartment is vacated and then rerented.

The tenant groups also bitterly denounced Council Member John Ray (D-At-Large), sponsor of the amendment. They complained that Ray's amendment will amount to windfall profits for Washington's landlords, who praised the provision as an incentive that is necessary to encourage them to keep vacated apartment units on the market and increase the city's dwindling housing stock.

The City Council is scheduled to give further consideration to the entire rent control bill today.

Ray proposed the amendment affecting rent increases for vacant apartments when the bill came up for a vote 11 days ago, and it passed on a 7-to-6 vote. The tenant groups accused Ray of "pulling a fast one" by not informing them in advance that he planned to introduce the provision.

"If Mr. Ray and the other council members who voted for this amendment were concerned about little people, they would be amending the bill to see to it that rent controls were extended to all rental units [including vacant ones]," said Khalil Abdel Alim, vice president of the Interfaith Conference of Metropolitan Washington, a member of the City-Wide Housing Coalition fighting Ray's amendment.

"The tenants, they want to hold the line, and I understand that," Ray said yesterday. "I see this amendment as a fair amendment which sends a little signal that says we're not going to kill the landlord and we're not going to kill the tenant."

The proposed city rent bill would tie rent increases to the cost of living in the Washington area.

Ray said that Washington landlords "need to have some encouragement" in the wake of a series of measures passed by the council during the last year that has been generally considered weighted towards tenant interests.

City law now makes it virtually impossible for landlords to convert apartment buildings to condominiums. Landlords are also forbidden by law from taking apartment buildings off the market and then later bringing the same building back into the market as a condominium, hotel, or anything other than an apartment building.

With spiraling rents, a shortage of available housing, especially for low and moderate income tenants, and with many landlords choosing to let apartment buildings sit vacant and boarded up, the council has been under considerable pressure to ease the restrictions on landlords to encourage the development of new housing in the city.

But rent control has emerged as the cause celebre for many city tenants, who outnumber homeowners in Washington by almost 3 to 1 and have organized themselves into an effective, citywide political force.

The council has found it too politically risky to entirely abolish rent control here, even though many of its proponents admit that rent control is at least partly responsible for the city's housing shortage. So rather than lift the controls, or allow them to pass quietly when the current law expires April 30, 1981, the idea of gradually phasing out rent control by allowing large increases on vacated units has won acceptance from a majority of council members, as well as landlords.

Rent control has been controversial in numerous large U.S. cities for years, with apartment owners and tenants battling each other in much the same way as in Washington. Now, a task force of public officials and urban specialists advising President-elect Ronald Reagan has unanimously recommended that federal grant money be withheld from any cities that have rent control laws. Currently about 200 municipalities have rent control.

Another federal study group, called the Council on Development Choices for the Eighties, recommended last week after a year's study that rent control laws be repealed. "We said that rent control is contributing to the decline of the rental housing stock," said committee staff director Laurence Houston, an official with the Department of Housing and Urban Development.