Food assistance to famine-stricken Ethiopia arose as a national issue yesterday, with House Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass.) attacking President Reagan's response to the drought and a presidential spokesman issuing a written statement describing Reagan's "personal interest" in the situation.

In the statement, White House spokesman Larry Speakes criticized the Marxist Ethiopian government for paying "little attention" to critical food needs and urged it to show "a more cooperative attitude" in getting help to the starving.

Speakes' statement, apparently spurred by growing debate over the Ethiopian situation, also said Reagan "has taken a personal interest in the famine situation in Africa, particularly the current crisis in Ethiopia" and has ordered that more U.S. help be provided.

The unusual election-season furor over U.S. assistance to a foreign country may have been sparked in part by an NBC-TV news broadcast last week of exclusive, dramatic footage from the British Broadcasting Corporation that showed corpses, emaciated children and weeping mothers in parched Ethiopia.

Network officials reported an "overwhelming" public reaction to the broadcast and private relief agencies said there was an outpouring of offers of help. "The switchboards were lit up here all day long," said an official of Catholic Relief Services, the main U.S. agency working in Ethiopia.

The Agency for International Development announced last week that the United States planned to add $10 million in food aid for Ethiopia this fiscal year, raising the total to $45 million -- a figure that some observers see as only a fraction of what is needed.

AID Administrator M. Peter McPherson coupled the announcement with criticism of the Ethiopian government's handling of the famine and compared the U.S. response with the "callous indifference" of the Soviet Union, a close ally of the Ethiopian regime.

The Soviet Union announced yesterday, however, that it was sending 300 trucks, 12 planes and 24 helicopters to distribute food to the starving. The U.S.S.R. had been under attack for providing $3 billion in weapons to Ethiopia's Marxist government but only 10,000 tons of rice. Critics of the Ethiopian government fear, however, that the trucks and planes might be diverted to help the government fight the civil war in the countryside.

The European Community also announced yesterday that it was making an emergency grant of nearly $22 million for relief efforts in Ethiopia, Mauritania, Niger, Mali and Chad, which are all suffering from famine.

The Ethiopian equation has been complicated by Washington's resistance to the government there. A prominent British food-aid expert, Dr. Charles Elliott, has charged that the United States and Britain have withheld assistance in the hope that a disastrous famine would topple the government.

U.S. officials, including Speakes yesterday, have noted a "greater interest" recently on the Ethiopian government's part in seeing more international help get to its people. McPherson is scheduled to meet here Thursday with Dawit Walde Giorgis, Ethiopia's relief commissioner, to talk about U.S. aid.

But O'Neill charged yesterday that the administration's response to the drought-driven food crisis in sub-Saharan Africa had fallen far short of what this country could provide. He said the administration "showed its true colors" earlier this year by stalling a congressional move to send more help to Africa.

"Even when the situation in Africa had become terrible, the administration held food aid legislative hostage to its murderous and illegal covert war in Nicaragua. If we did not give the Contras guns we could not give the Africans the food they need. It is a sad thing to say, but this administration has shown that it is ready to starve Africans so that it can kill Latin Americans," he said.

Rep. Mickey Leland (D-Tex.), chairman of the House Select Committee on Hunger and one of several congressional advocates of broader aid to Africa, urged last week that the administration provide direct government-to-government help for Ethiopia and that it give more logistical support to the private relief agencies that funnel U.S. contributions to that country.

O'Neill yesterday alluded to the NBC broadcast. "Something is wrong, very wrong," he said. "We turn on the evening news and we see African children starving to death -- and we get no explanation whatever of why we Americans are allowing this to happen."

Ethiopia's plight is part of a larger picture that the U.N. disaster relief coordinator described this week as the "worst human disaster in the recent history" of Africa.

The prolonged drought has left more than 35 million people desperately hungry and led to predictions that between 300,000 and 900,000 people will die in the next year unless an additional half-million tons of food is made available.