The Prince George's County Council approved a controversial affordable housing program yesterday that will require new developers to set aside a percentage of the homes they construct for low- and moderate-income families.

The program is part of a wide-ranging effort by county officials and a coalition of churches to increase the amount of affordable housing in the county.

The legislation, passed in two bills by votes of 7 to 0 and 6 to 1, mandates that developers of properties containing 50 units or more will have to lower the price of 10 percent of the units or contribute the cash equivalent.

The county has not yet decided on how to define moderately priced units. The program is scheduled to begin next year.

Yesterday's action also opened up some areas across the county zoned for single-family homes to allow town houses, a move that drew stiff opposition from many county residents who criticized it as a move to enrich developers at the expense of neighborhood integrity.

"Building row houses has nothing to do with affordable housing. It has to do with sardine living. It has to do with developer profits," said Walter Maloney, of Beltsville.

Supporters of the legislation say that permitting town houses allows developers to offer lower-priced housing and more units on the same amount of land.

"We are very happy that this passed," said the Rev. Bruce Eberhardt, housing council chairman of the Interfaith Action Communities, a church group. "We need to make sure that people who work in this county are able to afford homes here. This is a move in the right direction."

The church group is affiliated with the Industrial Areas Foundation, which has developed similar low-income housing programs in several cities.

About 250 lower-priced houses are expected to be built each year once the program is implemented, according to Eberhardt. The houses will be awarded by a lottery, with individuals submitting their names to the county Department of Housing and Community Development, according to Eberhardt. He estimated the prices of the homes, which are still being decided, would range from $70,000 to $80,000.

The average price of a single-family house in Prince George's County is more than $120,000. Although the county housing market is still less expensive than in areas such as Montgomery and Fairfax counties, prices have been rising. Several advocates of the program talked of how working people are forced to move to Calvert and Charles counties, while they work in Prince George's.

The Interfaith Action Communities and the county also are considering several other proposals to increase the amount of lower-priced housing in the county. They include: Construction of 1,000 town houses on county-owned land. Construction of 375 three- and four-bedroom houses on county-owned land that will sell for $75,000 each. Rehabilitation of 250 vacant or deteriorating houses by the county. Construction of 400 units of low-cost rental housing for senior citizens on county-owned land.

A similar program started in Montgomery County in 1973 has produced 7,524 houses for low- to middle-income families through the end of 1989, according to Terry McKinney, a program specialist for the Moderately Priced Housing Program.