The last of the whites held hostages for six harrowing days and nights in Zaire's southern mining center of Kolwezi were flown out of there on their way to Brussels yesterday amid reports of a mounting death toll among both Africans and Europeans caught in the rebel siege there.

Meanwhile, Zaire and Belgium exchanged angry words over the Belgian role in the rescue operation and remarks by Belgian officials casting doubt on charges by President Mobutu Sese Seko that Cubans were involved in the rebel action.

The latest unofficial estimates of the number of whites killed by the rebels range from 100 to 120, while hundreds of African civilians and military are said to have died during the occupation of the town.

THe fate of between a dozen and 60 other Europeans taken along with retreating rebels remined unknown. Meanwhile, French and Belgian para-troopers now in control of Kolwezi were still finding bodies as they searched through the pillaged homes and buildings of that once nicely kept copper mining town.

The Angolan-backed rebels, who reportedly moved into Zaire's Shaba Province nine days ago, are supporters of the independence state set up in the province - then called Katanga - in the early 1960s. THey fled to Angola when Katanga again became part of Zaire.

French military sourcea said their elite Foreign Legionnaries killed about 200 rebels in the final battle to drive them from Kolwezi Friday and Saturday while losing only two soldiers on their side. The Belgians reported on man wounded.

The Legionnaries were said to be 40 miles west of Kolwezi yesterday, still searching for the rebels thought to be heading for Angola where their camps were located. Most of the fighting in Shaba Province appeared to be over with only the situation in the railroad town of Mutshatsha still unclear. There are conlficting reports about which side now holds it, but some Western military sources were saying the Zairian army never lost it.

Several companies of Kantagans seem to be holding positions in an arch north and west of Klowezi three to five miles from the town, the French Armed Forces Ministry said in a battle communique.

The Kolwezi killings appear to be the worst slaughter of whites in any one spot on the African continent in recent times, far bloodier than anything that happened during the 1975-76 civil war in Angola or even during a rebellion, at Stanleyville, the northern Zairian town now called Kisangani, in 1964. At that time, about 40 whites were killed, before an American-Belgian operation ended the rebellion.

One old Belgian survivor of Stanleyville said there were no comparison between the two and no assurance that the same thing, only perhaps even worst, would not happen again here.

"It's finished," he remarked shaking his head sadly in an apparent reference to Zaire.

Indeed, it appears likely that Kolwezi will have far-reaching consequences not only for Zaire but on the general attitude of whites and the remaining white minority governments in southern Africa, hardening their attitude toward the proposed Western for the peaceful transfer of power to the black majority.

The toan was reported to be without food, water or electricity and dependent on outside supplies.

Meanwhile, a small contingent of Moroccan military advisers and soldiers arrived here, apparently to join the 2,700 French and Belgian para-troopers now involved in the Kolwezi rescue operation. Their role here was not immediately clear.

Here in Kinshasa, the main international airport was the scene of mass confusion as Belgian Boeing 707s crowded with European refugees from Kolwezi landed for refueling before taking off again for Europe. Zarian, American, French and Belgian military cargo aircraft shuttled in and out with supplies for the front more than 1,000 miles to the south.

As of midday, about 2,100 Europeans were reported to have been air-lifted out of Kolwezi with another 500 or so on their way out.

There are also hundreds of Zarians fleeing Kolwezi in fear of lives, mostly those who held jobs with the Belgian-Zairian mining company, Gecamines, and who lived in the European section of the city.

"We are afraid there is going to be a settling of personal accounts once the Belgian and French soldiers leave," explained one Zairian waiting to be taken away at Kolwezi airport. "This rescue of whites is fine but who is going to protect us afterward."

The Zairian refugee - an engineer for Gecamines - explained that blacks living in the European areas were envied by those living in the poor African quarters of Kolwezi.

Many blacks working for the government were rounded up by the rebels, who had their greatest support in the African quarters, and some were executed, although the refugee spoke of no mass killing of blanks.

As we was talking, a bus load of Zairians arrived at the airport hoping to be exacuated.

The French-Belgain rescue operation was exclusively for the whites.

Among the most fascinating spectacles at Kinshasa international airport was the arrival and departure os a huge American C5 Galaxy aircraft carrying jeeps, generators and other supplies to the capital of Shaba Province, Lubumbashi, several hundred miles to the east of the war zone.

U.S. Air Force C141s were flying in and out of the airport all day loaded mostly with gasoline and other fuels destined for Kamina, the major military airport 140 miles north of Kolwezi.

(President Carter told reporters in Plains, Ga., that the U.S. role in Zaire was "just about over. "He added that what we hear, the French and the Belgians and the Zairians have been successful.")

The Zairian government announced yesterday that it had paid $464,000 in outstanding debts to the United States to qualify for military credits. It said it had to forego "certain vital imports" to do so.

Hundreds of refugees milled about the Kinshasa airport clutching the few possessions or pets they had ben able to take with them . Many expressed bitterness and despair over the the terror of the past days and the failure of the Zairian army to protect Kolwezi.

It appeared that the 450 to 500 French living in the city were singled out for the worst treatment when it became known that French Foreign Legionnaries were to be dropped on the town.

The refugees reported that some rebels were extremely polite while others behaved like thugs.

Meanwhile, President Mobutu, who toured Shaba Province yesterday, lashed out at Belgium for what he called its "equivocial and strange attitude" since the beginning of the rebel insurgency. He took sharp issue with the statement of Belgian Foreign Minister Henri Simonet who cast doubt on Zairian claims of major Cuban involvement in the rebellion. Mobutu said all reports he had received while in Kolwezi Saturday agreed that Cubans were present in the town during its occupation by the rebels.

He said he trusted that Simonet's visit to the Angola capital of Luanda in June would include drinking a "goblet of blood" to the massacre of Belgiana families.

Belgium and Zaire appear to be close to a serious falling out, and some Belgians were refused entry into Zaire at the airport Saturday.

President Mobutu reportedly is also upset about Belgium's hesitancy to rush in and crush the rebellion in Kolwezi and its apparent desire to try to negotiate with the rebels instead. France, which is seeking to displace Belgium as the predominant outside influence in this former Belgian colony, is now enjoying high praise from the Zairian leader for its quick intervention.

Washington Post correspondant Ronald Koven reported from Paris:

French Defense Ministry spokeman continued to suggest that there is strong evidence that there were Cuban officers with the Kantangans when they arrived in Kolwezi, but he said that French forces have found no direct traces of the Cubans. The spokeman backed off a previous statement that there also were Soviet officers with the Kantangans.

French officials stressed privately that paris favors maintaining the unity of Zaire, whereas Belguim, when it gave the country its dependence, backed the secession of Shaba Province,then Kantanga, the main source of the country's mineral riches.

French state radio and television stressed statements by French and Belgian refugees approving the action of the French paratroopers to halt the atrocities that were graphically portrayed with many scenes of dead and multilated Europeans.

French reporters were shown asking the refugees how they reacted when the legionnaries arrived. The survivors all spoke of their joy and gratutude. The reports also stressed Belgian refugees critizing their own government for the slowness of the Belgian paratroopers' arrival in Kolwezi.

The film of the atrocities and the emotional accounts of European survivors seem likely to silence criticism that was growing against the operation from the French political opposition.

The conditions the French paratroopers found in Kolwezi are also considered likely to strengthen Giscard's already strong position as the host of a conference starting in Paris today of 21 french-speaking African nations. Twelve African presidents and a prime minister were expected for the conference that now seems sure to focus on the implication of the Zaire situation. Mobutu has been expected to attend, but it seems likely that he will be forced to stay home.

One proposal expected to get a major push at the conference is the creation of an African elite intervention force. Such a force, composed of units from different countries, might face difficulties if there were disputes among the contributing states over helping a particular government that did notenjoy universal support.