U.S. and Soviet diplomats will meet later this month for their first formal talks on Afghanistan in nearly three years, the State Department said yesterday.

Aide Kathleen Lang said the meeting, at a time and place to be announced, will seek "further clarification" of the views of the two governments. She said the talks are not considered "negotiations." Other officials said the talks are expected to be held in Washington.

The last U.S.-Soviet conference on Afghanistan took place in Moscow in July 1982 between U.S. Ambassador Arthur A. Hartman and Soviet Deputy Foreign Minister Georgi Kornienko.

The United States was working in concert with the United Nations on a political solution to the Soviet occupation of Afghanistan. Hopes were high in 1982 that such a solution was possible.

The prospects for a political solution have faded since then, but the potential for a change in Moscow's policies under the new leadership of Mikhail Gorbachev has raised an unusual degree of interest in probing the Soviet position.

U.N. Undersecretary General Diego Cordovez is planning the next set of "proximity talks" with Afghan and Pakistani senior officials for Geneva about June 20. Cordovez is reported to be hoping that the U.S.-Soviet discussions on Afghanistan will be held before then to give new impetus to the slow-moving U.N. talks.

Beyond the question of diplomatic change, there is also speculation that the Soviets under Gorbachev might seek decisive military change on the Afghan battlefield. Soviet and Afghan government forces have been taking the combat closer to the Afghan-Pakistan border, the key base and supply routes for the Afghan rebels. The rebel forces, meanwhile, are being aided by increasingly large and open U.S. support.

In a related development, a U.S.-Soviet round of regional discussions on southern Africa was held in Paris Thursday by Chester A. Crocker, assistant secretary of state for African affairs, and Vladillen Vasev, chief of the third Africa department of the Soviet Foreign Ministry.

The State Department said the Crocker-Vasev discussions centered on the security situation in southern Africa and "matters concerning the achievement of Namibian independence."

One of the central issues is whether, or to what extent, the Soviets will work against the withdrawal of Cuban troops from Angola. Such a pullout by the Cubans has been a sticking point for the United States and South Africa in moving toward independence for Namibia.

State Department sources declined to characterize the results of Thursday's talks, on grounds that both sides agreed to confidentiality. The sources said that no breakthroughs had been anticipated when the discussions began.

The U.S.-Soviet talks on southern Africa were the fourth set of discussions about that area since 1981. The last time the two nations held formal talks on the subject was December 1982.

The new sets of regional discussions between Washington and Moscow arise from President Reagan's proposal in a speech to the U.N. General Assembly in September that such talks be held on a regular basis.

The first set of talks was a U.S.-Soviet meeting on the Middle East, in Vienna in February.

Recently the Soviets expressed willingness to take up southern Africa and Afghanistan in regional talks.

Moscow is understood to be willing to hold similar talks with the United States on Latin America and Asian questions, but there has been no U.S. decision to pursue such discussions.