President Carter, citing a potential tragedy "of genocidal proportions," led an outpouring of action and oratory about Cambodia yesterday with a White House commitment of $69 million in relief assistance.

Carter announced his proposal in the press room of the executive mansion just minutes after a likely rival for the presidency, Sen. Edward M. Kennedy (D-Mass.), completed a strong attack on the administration for failing to move quickly enough to deal with the Cambodian famine. Kennedy spoke before television cameras and cheering students in a Georgetown University lecture hall.

On the day when concern about Cambodian starvation captured high-priority attention in official Washington, there were these additional developments:

About 40 church and secular leaders headed by the Rev. Theodore M. Hesburgh, president of Notre Dame University, appealed for private contributions as well as public action to avert a tragedy of unparalleled proportions. After a 20-minute meeting with Carter at the White House, Hesburgh expressed sastisfaction with the president's actions.

The private leaders, in a separate appeal to U.N. Secretary General Kurt Waldheim, proposed that U.S. and Soviet military forces under U.N. sponsorship undertake "an immediate massive airlift" of food and medical supplies to wartorn Cambodia.

The House Foreign Affairs Committee voted to authorize an additional $30 million in disaster relief aid to Cambodians. This fund, which has White House approval, is part of the $69 million in assistance announced by Carter.

U.S. Sens. James Sasser (D-Tenn.), John Danforth (R-Mo.) and Max Baucus (D-Mont.) flew to Phnom Pehn to confer with the Vietnamese-backed government on proposals for truck delivery of emergency food and medical supplies.

Foreign Minister Hun Sen took a lukewarm view of their proposal, saying in a broadcast interview that his government is able to distribute all relief supplies at present. Radio Phnom Penh attacked the plan as "unacceptable" and charged that "the U.S. war of aggression" in Indochina was responsible for the famine.

Intelligence reports of approaching famine in Cambodia surfaced early this year, following the Vietnamese invasion that ousted the Chinese-backed Pol Pot regime from Phnom Penh. The reports gained n volume and credence over the summer, when the major part of the Cambodian rice crop failed to be planted.

The United States called public attention to the impending famine beginning in July, and supported efforts by UNICEF and the International Committee of the Red Cross to negotiate with the rival regimes for the supervised supply of emergency food. It was only in late September that tentative agreement was reached with the Phnom Penh regime of Heng Samrin, which controls most of the country.

Hesburgh, quoting the State Department's refugee coordinator, Dick Clark estimated that Cambodia's population has been reduced from about 8 million to 4.7 million by war, execution and starvation in the past decade. He said 3 million people are now "in very dire straits," with some 200,000 a month expected to die unless food is quickly made available.

"We have in the making . . . another Holocaust," Hesburgh said, referring to the extermination of Jews by the Nazis.

Carter used similarly strong language when facing reporters, following a White House meeting with Hesburgh and the other leaders of the major faiths and charitable organizations. Also mentioning the Holocaust, the president declared that "this time we must act swiftly to save the men, women and children who are our brothers and sisters in God's family."

Of the new funds announced by Carter, $30 million will be the official U.S. response to an international appeal for $111 million made public last Friday by UNICEF and the Red Cross. An additional $9 million will go to Thailand for aid to Cambodians who have taken refuge there. These funds will be for the next six months.

The remaining$30 million, to be available over a year's time, is the money voted yesterday by the House committee.

Carter also called on all Americans to contribute private funds in "their synagogues and churches and otherwise" during the month of November until Thanksgiving to alleviate Cambodian suffering.

Kennedy, who as chairman of a subcommittee on refugees has a longstanding interest in international relief, charged that the United States did little or nothing in the face of reports for many months of a shortfall in Cambodian food production.

Recalling that Secretary of State Cyrus R. Vance, under questioning by Kennedy in a July 26 Senate hearing, described an urgent need to act, the senator charged, "Three months have passed, with no action by the government. Incredibly, the only movement was the heroic effort of the Red Cross and UNICEF to do the job alone."

Like the church and secular leaders. Kennedy urged "an immediate, massive airlift of food and medicine," and advocated the use of U.S. Air Force planes from the Philippines to drop food into areas of military conflict if necessary. He brushed aside a questioner's suggestion that the military equipment might involve the United States in the Cambodian war. CAPTION: Picture 1, Flanked by Cardinal Terence Cooke and the Rev. Theodore M. Hesburgh, right, President Carter announces $69 million commitment to Cambodian relief. By Frank Johnston -- The Washington Post Picture 2, Sen. Edward M. Kennedy . . . asks "immediate, massive airlift"