A group of American Indian families, tribes and organizations filed suit against the Department of Agriculture yesterday, charging that it has failed to implement federal food programs for reservations.

The class-action was filed on behalf of all impoverished Indians on about 300 reservations nationwide seeks a court order to force the USDA act by Jan. 1 on special provisions for Indians written into the Food Stamp Act in 1977.

An estimated 500,000 Indians of a 1 million population live in poverty. They have high incidences of obesity, tooth decay, diabetes and other diseases related to poor and insufficient diet, according to lawyers at the Food research and Action Center (FRAC), a public interest law firm that represents Indian groups involved in the litigation in Washington.

Most American Indians are scattered on reservations where unemployment is severe, transportation difficult and food stamp offices or grocery stores inaccessible. State and county governments who administer the stamp programs have shown minimal responsiveness to these problems, according to FRAC attorneys Ron Pollack and Rick Hart.

Congress wrote special provisions for reservation Indians when it revised the Food Stamp Act last year to eliminate the cash purchase price of stamps and lower the eligibility level so more poor people could qualify.

Reservation Indians, the only group that continued to receive, direct food distribution under the old commodities distribution plan when Congress made the food stamp program mandatory nationwide in 1974, were given the choice between stamps, commodities, or both.

The commodities program is better for Indians who cannot get to food stamp offices or grocery stores, FRAC lawyers argued. In 1977, USDA was required to upgrade the quality and amount of commodity foods. Indians have complained for years that the diet of low-protein, high-carbohydrate foodstuffs and monotonous canned goods makes their health problems worse.

The 1977 provisions also called for tribal administration of commodity and stamp programs where the state agency is too distant or has been ineffective in reaching eligible reservation Indians. Other changes made include an increase in federal funding for administrative costs and a requirement that states consult tribal leaders on operating the food stamp program.

Indian leaders were so confident that the congressional mandate would answer some of their food problems that food was not a major item on their grievance list during their "Longest Walk" campaign last summer, FRAC spokesman said.

The suit charged, however, that USDA has created "unreasonable delays" in making the mandated changes. The delays the suit says, have violated the Indians' rights and deprived them of aid during a period of rising food prices that makes their needs "greater than ever."

USDA officials say they were delayed in preparing regulations on the Indian provisions because of the extensive general revisions, to the law and by USDA special efforts to involve tribal leaders in the process, including an all-day meeting with FRAC and Indian officials in September.

"It is somewhat strange to meet for a day and a half with some people and carefully consider their comments, then he sued for taking the time to incorporate changes based on their comments," Assistant Agriculture secretary Carol Foreman said in a statement yesterday.

The suit, which names 29 poor families and 10 tribes, is "imminently reasonable," according to FRAC deputy director Jeffrey Kirsch. Kirsch said USDA predicted it would complete the regulations by mid-October, when first warned of a lawsuit in September, but later retracted the schedule, saying the delays would be indefinite.

"Our lives have been toyed with long enough," Robert Price, food director for the Papago, one of the tribes named, said when reached by telephone in Sells, Ariz. "Our people deserve to eat, and to eat well. That's not asking too much."

Robert Greenstein, assistant to Agriculture Secretary Bob Bergland, said that the staff writing Indian regulations had been preoccupied with the larger package of 1977 revisions until mid-October. The agency "does not have unlimited staff," he said.

"Why should Indian people subsisting on inadequate food have to respect their staffing problems?" Kirsch said. "It's asking too much."