The chief foreign spokesman for the pro-Western rebels fighting the Soviet-backed Marxist regime in Angola says that recent congressional action repealing the ban on U.S. military aid to his group was "a very encouraging change" in U.S. policy.

But Jeremias K. Chitunda added in an interview that the rebels seek only "unambiguous political and moral support" from Washington.

Chitunda disclosed that his National Union for the Total Independence of Angola (UNITA) had been making plans to attack the main oil facility in northern Angola when South Africans staged a raid on it May 21. The facility is partly owned by Gulf Oil.

Chitunda, UNITA's foreign affairs secretary, charged that Gulf Oil was "subsidizing" the Soviet and Cuban "occupation" of Angola as well as the Marxist Angolan government's war against UNITA, which he estimated cost $4 million a day.

"Today, Gulf Oil has got its fingers practically dripping with the blood of the Angolan people," he said. "Can we stand by just watching Gulf Oil continue to do what it is and not react? No, we can't."

The South African raid came, he said, just as UNITA was acquiring the technical know-how and "advancing its preparations to undertake such activities" to knock out the oil production facilities in northern Cabinda district.

The raid complicated UNITA's task, he said, by causing the Angolan government to triple its vigilance and by undermining UNITA's credibility.

"Anything we do in Cabinda, people will say, 'You see that may be the hand of South Africa again.' So, militarily, they the South Africans make it difficult for us now to carry out our programs against Gulf Oil installations in Cabinda."

Chitunda's comments about UNITA's intentions to put Gulf Oil out of operation underscored the complex nature of the question before Congress and the administration of whether to resume military or any other kind of assistance to UNITA, which the Central Intelligence Agency aided during the 1975-76 civil war until Congress stopped it.

Gulf Oil holds a 49 percent interest in and operates Angola's main oil-producing company. It constitutes the main U.S. investment in that country as well as the Angolan government's chief source of foreign revenue.

Congress has yet to take final action to reverse a 1976 prohibition on aid to UNITA and the Reagan administration has said it has "no plans" to resume assistance.

Chitunda said UNITA neither seeks nor needs military assistance from the United States, although he said UNITA feels that any humanitarian aid to Angola should be distributed on an "even-handed" basis between the Angolan government and his group, according to the population each side controls. He claimed UNITA has 3.7 million of Angola's 7 million people, mostly in the southern half of Angola.

The United States has earmarked $12 million this fiscal year in indirect emergency assistance for Angola through relief agencies such as the Geneva-based International Red Cross.

Chitunda's main request, however, is for Washington to use the repeal on the ban of aid to UNITA as "a stick" to pressure the Marxist government into negotiations on a political settlement that would end the decade-long civil war and secure the withdrawal of the 25,000 to 30,000 Cuban troops stationed in Angola.

"We expect to get from the United States a strong and unambiguous political and moral support to resolve the basic questions of national reconciliation, the withdrawal of all foreign forces from Angola, the holding of free elections and the creation of durable democratic institutions for our people," he said.

Chitunda said he did not believe the Angolan government would adhere for long to its decision last week to break off talks with the United States on withdrawal of Cuban troops and holding of U.N.-supervised elections in neighboring South African-administered Namibia. The decision was made in retaliation for Congress' lifting the ban on aid to UNITA.

Calling it "a temporary outburst" of anger, Chitunda predicted that the Marxist government would "very soon" return to negotiations because, he said, "we know the thing it dreads the most is the possibility of United States assistance to UNITA."

The United States must continue its diplomatic efforts because, he said, "everybody recognizes the fact that only the United States can carry out this diplomatic brokerage."