President Carter, in a major shift in American nuclear energy policy, ended government support for the production of plutonium yesterday and called on other advanced nations to join the United States in halting the spread of the deadly nuclear fuel around the world.

In a statement at the White House, the President set out the steps, the United States will take to control nuclear proliferation and said he will seek agreements with foreign governments that would put a lid on the number of countries with access to plutonium, which is used to fabricate nuclear weapons.

Specifically, Carter said that the United States will:

Defer indefinitely the commercial reprocessing and recycling of the plutonium that is found in spent fuel from conventional nuclear uranium-burning power plants. Carter said that a privately financed plant at Barnwell, S.C., that is designed to reprocess plutonium "will receive neither federal encouragement nor funding" for its completion. It is considered unlikely that the plant will be completed without federal assistance to pay some of the remaining construction costs, estimated at $250 million or more.

Cut back the government-sponsored Clinch River, Tenn., breeder reactor project to an "experimental basis," indefinitely dalaying its development as a commercial prototype.The demonstration liquid metal fast breeder reactor, which was to be operational by the mid-1980s, is designed to burn reprocessed plutonium as a fuel and "breed" additional plutonium, which in turn could be reused as a fuel.

Place greater emphasis on breeder reactor designs that do not use plutonium as a fuel and eccelerate research on nuclear fuels that cannot be turned into nuclear weapons, as plutonium can be.

Increase capacity to produce enriched uranium, the conventional nuclear fuel, and seek contracts to supply the fuel to other nations, thereby lessening their dependence on plutonium.

Continue to embargo the export of equipment or technology that would permit uranium enrichment or chemical reprocessing.

While Carter's actions yesterday pulled the United States out of the plutonium production business, it by no means guarantees a halt to the spread of plutonium, and with it the capacity to produce nuclear weapons, around the world.

This is because four other nations - West Germany, Japan, France and Britain - already have the capacity to reprocess plutonium, and several other nations, in the President's words, "are on the verge of becoming nuclear explosive powers."

Carter emphasized that the United States has neither the authority nor the desire to impose its own plutonium policy on these countries, but the appealed to them to "form an alliance that might be fairly uniform in this respect."

"They have a perfect right to go ahead and continue their own reprocessing efforts," he said. "But we hope they will join with us in eliminating in the future additional countries that might have had this capability evolve."

The present generation of nuclear power plants, such as those now in use in the United States, burn lightly enriched uranium, which is not weapons-grade material. But because of fear that the supply of uranium will dwindle, there is pressure to convert to a more sophisticated generation of plutonium-burning reactors. It is the reprocessed plutonium burned in these reactors that can be fabricated into nuclear weapons.

The pressure to convert to plutonium reactors is particularly strong on nations such as West Germany and Japan, which lack the United States' reserves in coal and uranium for fuel.

Thus, the success the President has in turning this own anti-plutonium policy into an effective tool against nuclear proliferation will depend largely on negotiations with foreign governments, beginning with the summit conference he will attend next month in London.

An administration official said that when the United States' nuclear allies were shown a draft of the new policy about 10 days ago their reactions were hostile. Citing their own dependence in imported sources of energy, these countries rejected Carter's contention of yesterday that there is "strong scientific and economic evidence" to support a shift away from the rush toward plutonium reactors, the official said.

Carter's conciliatory tone yesterday and his emphasis that the United States would not attempt to impose its will on the other nuclear nations resulted in part from this initially hostile reaction, he said.