Warning that Africa faces the world's most "severe hunger problem," the head of the Agency for International Development yesterday said the United States is seeking to ensure that more food is available there. As part of that effort, he announced a $3 million allotment for food aid to Ethiopia next year.

AID Administrator M. Peter McPherson and Secretary of Agriculture John R. Block, in comments about the world food situation, told the House Foreign Affairs Committee that the hunger situation through much of the rest of the world has improved in the past 10 years.

McPherson said, "Food consumption has increased significantly in Asia, Latin American and the Near East" and the "percentage of people in the world today who are hungry is less than 10 years ago. But the number overall is greater because of population growth." He said Asia still has the largest number of hungry people, but the proportion to the total population is less than in Africa.

Yet both men, acknowledging that enough food is available to feed the world's hungry, said problems come in trying to get it distributed and paid for. "There is a no shortage of food" in the world, Block said. "We have enormous stocks of food in the United States . . . . The problem is who is going to move it and pay the freight."

Block and McPherson agreed that the problem in Africa is growing.

"The situation in Africa is really very bad, and it is deteriorating," McPherson said. "The average person in sub-Saharan Africa has less calorie intake than five years ago."

He pointed to a wide drought on the continent, civil unrest, lack of infrastructure to provide food and low food production, all of which have contributed to leaving a "large proportion of the population at the chronic malnutrition level." A high rate of population growth has added to the problems, he said.

Ethiopia is among the hardest hit countries. U.N. officials have estimated that 50 to 100 children are dying daily and 3 million people are affected by the food shortages there caused by a drought and prolonged civil wars.

The issue of U.S. aid to Ethiopia, which is allied with the Soviet Union and has about 12,000 Cuban troops on its territory, has become a sensitive one between the Reagan administration and some congressional critics who say the United States has been too slow to respond to the crisis and given too little. Relief officials have charged that the United States is reluctant to aid Ethiopia because of its close ties to Moscow. Administration officials have denied this.

Before today's announcement, emergency U.S. aid to Ethiopia since May totaled about $2.3 million.

The $3 million program announced yesterday provides 10,000 tons of food to feed 178,000 people in a continuation of a nonemergency program run by Catholic Relief Services with U.S. funding for several years. The administration this spring had dropped the program from its 1984 budget request.

McPherson also announced that $700,000 is being given to Catholic Relief Services to rent vehicles for emergency food transportation for U.S. supplies. Relief officials have termed transportation their biggest need in Ethiopia.

Rep. Howard Wolpe (D-Mich.), chairman of the Foreign Affairs subcommittee on Africa and a leading critic of the U.S. response in Ethiopia, applauded McPherson's announcements but cautioned that more aid could still be needed.

Block also acknowledged the problems in Africa, where he said "it would take some time" to reach "food security." He urged developing countries to increase production by discontinuing policies under which farmers are paid at an artificially low rate for their produce. He defended U.S. policies despite questioning by Wolpe on the incongruity of world hunger and the U.S. policy of seeking to get its own farmers to cut production.

"We provide more food aid than all the rest of the world countries put together," he told the committee members. But he acknowledged that the United States ranks 17th among industrialized countries when food aid is considered as a percentage of gross national product.