Safeway, Giant Food and A & P supermarket chains said yesterday that they are freezing prices temporarily on a limited number of their private-label products as part of an anti-inflation move.

The freeze at Safeway and A & P stores went into effect yesterday and will last for 30 days. Giant's freeze will go into effect Sunday and continue for 21 weeks.

The savings for individuals buying weekly market baskets of groceries could not be determined immediately.

None of the chains would say how much money their companies might lose because of the freeze.

"We don't know," said Felicia del Campo, a Safeway representative. Barry Scher, a Giant spokesman, said his company hopes to avoid any loss. "We hope volume (of sales) will increase as a result of this program," he said.

Supermarkets, as a matter of pricing policy, make a higher profit on their house-brand products than on national brands.

The Safeway freeze includes about 180 Scotch Buy brands of food and nonfood items. Scotch Buy is the only one of Safeway's private labels to be affected by the freeze.

Giant's freeze is broader and longer. About 275 Giant brand food and household items will be frozen. In addition, Giant is freezing prices on about 100 generic prescription drugs and drug notions.

A&P said its freeze would cover its extensive Ann Page private label items, and hundreds of other generic products, but the full extent of merchandise affected was uncertain late last night.

Safeway has about 130 stores in the Washington area, Giant about 100, and A&P 42.

Safeway and Giant which control 60 percent of the local food market, said that they will decide at the end of their announced freeze periods whether to continue the freezes.

Products covered by the price ceiling include basic staples such as flour, canned vegetables and meats, coffee and peanut butter. Some nonfood items such as detergents, fabric softeners and paper products, also are parts of the freeze.

The Safeway program does not include any fresh meats, fresh dairy products or fresh produce.

The Giant price freeze will affect a number of the chain's private labels, including Giant Food, Aunt Nellie's Heidi, Kiss and Kitchen Queen.

A handful of national brand prices will remain frozen at Giant, including Armour Star frozen turkey and Mohawk canned hams.

In addition, the Giant freeze will cover regular ground beef -- but not lean or extra lean ground beef -- mixed chicken fryer parts and some cheeses. Giant drugstore products in volved include 107 prescription generic drugs and all insulin products and disposable hypoderic needles and disposable syringes.

If the cost of any of the products on the lists should decrease during the period in which prices are frozen, retail prices would be lowered accordingly, officials for Giant and Safeway chains said.

They also said they will not raise prices on other items to make up for losses due to the freeze. Nor do the chains plan to bump up prices at the end of the freeze to compensate for increases that were not made because of the price ceiling, officials said.

"We won't try to recoup . . . We will swallow all of the increases that are not made during the 30-day freeze," the Safeway spokesman said.

In announcing their freeze plans, all three companies said they were responding to a request made by Esther Peterson, the president's special assistant on consumer affairs.

In the words of one Safeway official, "This was done as a result of Miss Esther calling."

Peterson said she had written letters to about 50 supermarket chains through the country suggesting that they initiate a voluntary price ceiling program to "ease the inflationary pressures that are causing such hardships for all consumers."

She said she was writing because "the president has asked me to determine what more we can do to keep the cost of food from rising so rapidly." Mandatory controls would be unproductive, Peterson said. But a voluntary price ceiling on "some commonly purchased food products" would help, she said.

Peterson said yesterday that she followed up her letters with telephone calls to about 20 of the companies.

"Giant responded first," she said yesterday, and promised to initiate a freeze. Peterson formerly worked as a consumer adviser for the chain.

Safeway was first to make a public announcement of its plan and to put the freeze into effect. Giant countered within hours with its announcement or a more extensive program.

Questions were raised yesterday by lie consumer-oriented economist about the effectiveness of a food price ceiling at a time when consumers are being much harder hit by other living cost increases.

". . . it is a marginal step in the right direction, said Gar Alperovitz, codirector of the National Center for Economic Alternatives, a new research institute concentrating on the effect of inflation on basic necessities.

The food ceiling, he said, is like a "minor trickle" when compared to the tidal wave of energy cost interest rates.

Food prices have been increasing at a slower rate than other components in the U.S. Consumer Price Index.

According to government economists, the nine-tenths of 1 percent increase for food in the unadjusted index during January was considerably below the 1.5 percent increase in prices for nonfood items.

The economists said that food prices have risen less than half as fast as nonfood prices during the last six months and thus helped to moderate the general rate of inflation.