Arlington County officials said yesterday that a proposal by some residents of the Lee Gardens apartments to form a cooperative and purchase more than 80 units of the complex could jeopardize an agreement with the developer to preserve 200 of the units as low- and moderate-income housing.

The Artery Organization of Bethesda, which is engaged in an expensive renovation of Lee Gardens, recently agreed to sell the 364 units in the north section of the complex to the nonprofit Arlington Housing Corp. Of those units, 200 would be set aside for tenants who qualify for federal rent subsidies, and the rest would be rented at market rates. The sale is expected to go to settlement Aug. 26.

While praising joint tenant and county efforts that will lead to the preservation of the 200 units for low-income families, some tenants signed a letter saying they "are distressed that more has not been done to save the remaining 164 units in North Lee Gardens for us . . . . The market rents that are to be charged for those units are beyond the means of most of us."

The tenants association proposed the creation of a tenant cooperative that would buy 86 units that would otherwise be rented at market rates.

Such a plan could jeopardize $33.6 million in financing from the state-chartered Virginia Housing Development Authority, said county board member Mary Margaret Whipple. The financing will enable the Arlington Housing Corp. to buy the north section of Lee Gardens from Artery.

County Board Chairman Albert C. Eisenberg said the county is willing to help the tenants form a cooperative at another location. Tenant spokeswoman Julieta A. Nelson said they will study the financial arrangements of the sale, and "if there is no way to go forward, we will accept that," and then try to form a cooperative elsewhere.