The United States and Pakistan have begun preliminary contacts aimed at resolving their dispute over Pakistan's planned purchase from France of a nuclear processing plant. Such a plant would be capable of manufacturing the raw material for atomic weapons.

Informed sources said State Department and Pakistani officials will prob-talks on the touchy issue. Pakistan's Prime Minister Zulfiquar Ali Bhutto signaled his willingness to undertake the discussions following the recent national elections there.

Calling the reprocessing question "a live and active issue" with the United States, Bhutto told reporters that he is prepared for a "bonafide and genuine discussion" now that elections both in his country and in the United States are over.

A statement yesterday by India's new prime minister, Morarji Desai, suggesting a change in New Delhi's nuclear policy, could have major impact on the negotiations with Pakistan. Desai declared his government does not believe in atomic weapons and he did not know whether "peaceful nuclear explosions" are necessary. "If it is not necessary, it should never be done," he said!

India's 1974 atomic blast, which that country claimed was a "peaceful nuclear explosion," spurred Pakistan's determination to acquire a nuclear explosive capability. An Indian decision to halt its "peaceful nuclear explosion" program might bring a major change in Pakistani thinking and have impact elsewhere in the less developed world.

President Carter, during last year's campaign, expressed strong opposition to the French sale of a nuclear reprocessing plant to Pakistan and a similar West German sale to Brazil. Deputy Secretary of State Warren Christopher has already begun talks with Germany and Brazil about their nuclear deal, so far without success.

Carter has launched a government wide review of U.S. policy toward nuclear reprocessing at home and abroad and has hinted broadly that a major shift against reprocessing is likely.

Despite the current review, the Energy Research and Development Administration last Thursday approved preliminary steps by Spain to reprocess U.S.-supplied nuclear fuel in England. This was the first such approval of commercial reprocessing steps abroad by the Carter administration, but evidently was taken without checking with the White House.

An ERDA official said the State Department had been consulted about the Spanish case and the State "coordinated" the views of the Arms Control and Disarmament Agency and the Nuclear Regulatory Agency. Both the ERDA official and an official of the National Security Council said they knew of no White House involvement.

The approval of the Spanish application was justfied on the basis of an "urgent need" claimed by Spain to transfer irradiated fuel elements from the Garona power reactor to England for eventual reprocessing. Spain reportedly told U.S. officials here and in Madrid that the power reactor would have to be shut down if the transfer application was not approved, because storage space for the dangerous materials in Spain is entirely occupied. The reactor is said to supply four per cent of Spain's power needs.

Two House International Relations subcommittees are scheduled to begin hearings early next month on U.S. approval of overseas reprocessing such as the recent Spanish case and similar actions taken Dec. 30 by the Ford administration.

Natural or lightly enriched nuclear fuel is not usable in atomic explosions, even after being irradiated in a nuclear reactor. However, "reprocessing" is an operation to separate plutonium - a weapons material - from other elements of irradiated fuel. Thus reprocessing poses a major risk of nuclear weapons proliferation.