Angolan will send home the 20,000 Cuban soldiers that have been there since 1975 if Western-sponsored negotiations with South Africa result in full independence for the disputed territory of Namibia, Angolan Foreign Minister Paolo T. Jorge said.

"When Namibia will be independent, and the aggression against Angola from South Africa finished, then we will say to the Cuban comrades, 'Thank you very much, you can go home now,'" Jorge said in an interview with The Washington Post here last night.

But the Angolan diplomat, in New York for this week's Security Council debate on the imposition of sanctions against South Africa, said that the Reagan administration's early signals on its African policy have dimmed hopes for a peaceful settlement of the Namibian conflict.

Striking from its bases in Namibia, which lies on Angola's southern frontier, South Africa has staged increasingly heavy raids into Angola to attack Namibian guerrilla concentrations and the Angolan military. Jorge said the Cuban troops remained to protect the country against a full-scale invasion by the South African forces, who he claimed have killed 1,800 Angolans in the past three years. Namibian guerrillas operate out of Angola.

Jorge also suggested that a resumption of U.S. aid to Angolan rebel leader Jonas Savimbi would not only start a diplomatic confrontation between black Africa and Washington but would also imperil the economic interests of American firms that have invested at least $200 million in Angola and plan to put $500 million in new oil investment there in the near future.

President Reagan and his ambassador to the United Nations, Jeane J. Kirkpatrick, have voiced admiration for Savimbi, who is fighting a guerrilla war against the government in Luanda with South African support, and the administration is seeking the repeal of a congressional amendment that bans covert or overt U.S. aid to Angolan rebels.

Kirkpatrick has said that repeal of the legislation, known as the Clark Amendment after its sponsor, former senator Dick Clark (D-Iowa), is a matter of principle and is sought only because it places restrictions on the executive power of the president. In a television interview earlier this week, she said that the administration has "no present plans" to aid Savimbi, but did not rule out future aid.Speaking in Washington today Secretary of State Alexander M. Haig Jr. also said that the legislative repeal would not prejudge the question of aid to Savimbi.

Such comments have convinced some African and Western diplomats that the Reagan administration is holding out at least a threat that it intends to try to drive the Cubans out of Angola through confrontation if the Angolans do not turn away from the Cubans and the Soviet Union and turn to the United States for support. Haig, speaking to the American Society of Newspaper Editors, indicated that the administration would not recognize the Luanda government as long as it continued to permit the Cuban presence, which Haig called "a violation of international order."

Throughout his comments, Jorge, who is a member of the Central Committee of the ruling Popular Movement for the Liberation of Angola, laid heavy emphasis of his government's desire to have good political and economic relations with the United States. He said that his government would not be upset by the repeal of the Clark Amendment if Washington would first formally recognize the government in Luanda and establish diplomatic relations, as a sign that Washington did not intend to destabize the government.

After participating in the Security Council debate on Namibia Thursday, Jorge was the guest of honor at a New York dinner attended by a dozen representatives of some of America's largest corporations, including Chase Manhattan Bank, Texaco, Boeing and Gulf Oil. Gulf plans to double its 100,000-barrel a day production in Angola by investing $100 million a year for the next five years, and Gulf executives have publicly urged the U.S. government to treat Angola as "a knowledgeable, understanding and reliable business partner."

But Jorge suggested in the interview significantly increased tension between Washington and Luanda might result in a shift of business toward European countries.

"We intend that the further economic and commercial development will be envisaged in a political and diplomatic framework . . . The economic cooperation between states can be affected" by diplomatic confrontation. "But we will continue to encourage foreign investment and to seek foreign technology."

He pointed out several times that Angola had full diplomatic relations with Canada, France, Britain and West Germany, the four major Western nations that have joined the United States in seeking a negotiated settlement in Namibia, and is increasing commercial relations with them. France doubled its exports to Angola last year, and French oil companies have concluded prospecting agreements with Luanda.

Angola has played a key role in pressing the guerrilla leadership of the South West African People's Organization (SWAPO), which is based in Angola, to participate in the negotiations on Namibia, formerly known as South West Africa. The three-year-old negotiations involve the five Western nations, known as the Contact Group, the United Nations and South Africa, the occupying power in Namibia since World War I.

Despite disappointment over a shift in U.S. position described to him by Assistant Secretary of State-designate Chester A. Crocker in Luanda last week, Jorge said Angola "is not closing the door on negotiations on Namibia. We want the United Nations plan that has been agreed on, which was in fact elaborated by the Contact Group, to be implemented without delay or modification."

The Reagan administration has introduced the idea of writing a constitution to provide guarantees to Namibia's white minority before independence and is ambiguous about its support for the predominant U.N. role that the original Contact Group plan had outlined.

American insistence on the removal of Cuban troops as a precondition for diplomatic relations "is a clear interference in our affairs," he said sharply. "Why do the Americans not talk about the French troops in Djibouti? Why do the Americans keep troops in Korea, in Germany and in Cuba, but object to Cubans being here?"

He also said any suggestion that relations could be established only if Savimbi were to become part of the government in Luanda would be rejected.

"I don't see any possibilities of what American officials talk of as reconciliation," he said. "We do not accept reconciliation with traitors and terrorists. Savimbi represents nothing in my country. It is shocking to hear the president of the United States say that UNITA [Savimbi's organization] controls one-half of Angola when it does not control a single province. UNITA can infiltrate, can sabotage, but that is all. Just as the United States cannot control all of its border with Mexico, we cannot control all of our frontier."