Morocco is willing to organize and staff a pan-African army of 20,000 to protect Angola's borders if Angolan President Agostinho Neto would send Cuban troops home, Morocco's King Hassan II has announced.

Hassan, in Washington this week to visit President Carter, mentioned the proposal in an interview at Blair House. He acknowledged that it is unlikely that Neto would accept, but he put the proposal forward to demonstrate that Neto had other alternatives than than Cuban force to prevent attacks into Angola from South Africa.

The offer to replace the estimated 25,000 Cubans in Angola was reinforced yesterday by a joint statement in which President Carter and the king condemned foreign interventions in Africa "ad the arms races which have been their result." Hassan, who left Washignton Thursday, arrived in Morocco yesterday.

"We will have some difficulty in believing that President Neto's desire for reconciliation is sincere until he tells the Cubans to go home," the Moroccan monarch said in the interview, shortly before leaving Washington. Reminded that the Angolans feel vulnerable to South African raids, Hassan said:

"Apartheid is an African problem, and should be dealt with by Africa. If there is a shortage of troops to defend Angola against South Africa, we can bring them from Egypt, from the Sudan, from Nigeria, from Morocco. We are ready to send an inter-African force of 20,000 soldiers if President Neto wants it. But I doubt that he does."

Morocco continues to maintain a force of about 1,500 soldiers in Zaire's Shaba Province, although they are reportedly preparing to return home in a matter of months. Hassan dispatched them to Zaire in June, after Katangese rebels based in Angola struck into Shaba and then retreated.

The incursion touched off an international uproar, which continues to reverberate in world capitals. President Carter's national security affairs adviser, Zbigniew Brezezinski, and other officials publicly took the Soviets, Cubans and Angolians to task for allowing or aiding the invasion.

Earlier in the Carter administration, Andrew Young, U.S. ambassador to the United Nations, said that the Cubans were a force for stability in Angola.

Hassan's Angola offer came as U.S. diplomats resumed their efforts to assess personally the reconciliation that Neto has constructed with Zaire and the West since the Shaba turmoil.

Assistant Secretary of State for African Affairs RIchard Moose and U.N. Deputy Ambassador Donald McHenry are to stop off in the Angolan capital of Luanda next week for official discussions, the State Department announced yesterday.

McHenry, who visited Luanda in June, and Moose are on their way to a U.S.-African conference in the Sudan.

After McHenry's visit, Zaire and Angola resumed diplomatic relations, and the Katanganese bases on Zaire's border were dismantled. U.S. officials now assert in private that the Carter administration's "firmness" in June forced Angola to make peace with its neighbors, a view sharply disputed by other U.S. policy makers.

There have been no reports of changes in the force levels of the Cuban troops, who came to Angola in late 1975 to help Neto's guerrilla movement fight two other Angolan nationalist movements backed by the United States and South Africa.

Diplomatic sources at the United Nations report that the Cuban forces have prevented at least one and perhaps two coup efforts mounted against Neto by Angolan forces more closely alligned with the Soviet Union than is Neto. But the sources offered no evidence to support the assertions.

In a related development, the White House announced that Young will visit Guinea next week as part of a wide-ranging Africa trip that will also include a stop in Luanda.

Washington has been gradually stepping up its attentions to Guinea's president, Sekou Toure, as he increasingly emerges from a decade of isolation and radical Marxism. This YEAR Sekou has made peace with his neighbors and made overtures to the West.

King Hassan gave the hour-long interview in the parlor of Blair House Thursday morning shortly after he had breakfast with Henry A. Kissinger, secretary of state during the 1975 U.S. covert operations in Angola, and after a meeting with Robert S. McNamara, World Bank president. The king appeared relaxed and clearly buoyed by his two days of meetings with President Carter.

In contrast to the pointed criticisms of the Carter administration's foreign policy he voiced in a similar interview in May in Fez, Hassan's comments on Carter Thursday were landatory. He said that Carter "gained the equivalent of one year of experience in foreign affairs in 12 days' of negotiating at Camp David with Egyptian President Anwar Sadat and Israel's Prime Minister Menachem Begin.

But Hassan, one of Sadat's closest Arab allies, again refused to give his unqualified endorsement to the Camp David framework accords, which he compared at this stage to "a jigsaw puzzle that still has to be put together. I cannot endorse it piece by piece. I will be able to approve it when it is completed."

Asked about the arms package that the United States has declined to sell to Morocco because of a lack of assurances that the arms will not be used in the Western Sahara territory against Polisario rebels, the king said that he had not negotiated any arms contracts during his visits.

Diplomatic sources said later that Morocco had again failed to give the administration the assurances it needs to open the way for the sale.