Food, fuel and housing price increase hit Americans hard again in March, as consumer prices rose another I percent, the Labor Department reported yesterday.

With the consumer price index up 10.2 percent in the last 12 months and rising at an annual rate of 13 percent in the past three months, President Carter's anti-inflation chief Alfred Kahn conceded, "We clearly do have double-digit inflation."

Kahn also warned again of "some bad months ahead" but predicted a "tapering of inflation" after that. But he also declared pointedly that the "only hope for real relief" is slowing down the economy.

The only mildly good news has that food prices, and the entire index, rose less rapidly than in the preceding month. Kahn noted that food costs rose 1 percent, compared to a 1.6 percent jump in February and a 1.4 percent rise in January.

Howard Hjort, chief economist at the Agriculture Department, said that because of larger supplies of pork and poultry, "the statistics do indicate a significant slowdown in the rate of food price increases." And he added, "That patern will continue for the rest of the year."

Calling the March CPI increase "an economic and political disaster," Sen. George McGovern (D-S.D.) announced at a Joint Economic Committee hearing that he would introduce legislation providing the president standby authority to impose wage and price controls.

Kahn responded at the hearing, "I think giving the president that authority now would be misinterpreted and surely would be counterproductive."

The availability of controls authority "would set off a round of anticipatory price increase" by companies who feared that it would be true "particularly now with so little slack in the economy," he added.

Kahn stressed that the most inflationary parts of the CPI-food, energy and housing-were not areas in which companies have significant monopoly power that might be curbed by controls.

While he noted that improvement in food price behavior, Kahn said that on the energy front the "news and prospects are bad." Gasoline prices rose almost 4 percent in March, which he said was a result of a combination of oil cartel price increases and a decline in production of lower-priced domestic crude.

Kahn said the recent increases-gasoline prices have been rising at a 35.6 percent annual rate for the last three months-are not related to Carter's plan to decontrol oil prices.

"Decontrol or no decontrol," he said, "we can't avoid doubled-digit inflation in energy." He went on to defend the plan, despite its inflationary implications, saying, "In the long run, we do the American people no favor by trying to hold the price of energy below its replacement cost. . . We simply have to learn to live with higher energy costs."

Administration officials continue to worry that the continuing high inflation rates will completely undermine the already tottering wage-price standards. Yesterday, Labor Secretary Ray Marshall said that March increase "makes it difficult for us, obviously . . . I think it will be very difficult to continue the program unless we show some progress on the price side."

At the White House, press secretary Jody Powell issued a statement indicating that the administration still intends to try to enforce the wage standard. He would name no names, but the target obviously was the leaders of the United Auto Workers and the United Rubber Workers unions and others who have been telling the administration to stay out of wage negotiations.

"Such suggestions are wishful thinking," Powell said. "The president believes the American people have a legitimate interest in decisions affecting their welfare. The president intends to continue to do what he can to represent that public interest."

The largest percentage increase in any category in the CPI in March was a 4.7 percent rise in the cost of fuel oil, coal and bottled gas. Gasoline was next at 3.8 percent, followed by 2.5 percent for meats, poultry, fish and eggs.

Fresh fruits and vegetables, which had risen more than 4 percent in the previous two months, fell I percent. In the only other significant drop, used car prices went down 0.3 percent.

Over the last 2 months, by far the largest increases were in the meats category, which was up far more. The cost of financing, taxes and insurance for homeowners was up 17.5 percent, primarily because of higher mortages interest rates. If interest rates had not risen at all, the CPI would have risen 9.1 percent insteead of 10.2 percent.

The March increase in the index put it at 209.1, cmpared to the 1967 base to 100. CAPTION: Graph, no caption, The Washington Post. Picture, ALFRED KAHN . . . "some bad months ahead"