The rebel invasion of Kolwezi that began at 6 a.m. Saturday, March 13, was without a doubt one of the best planned and executed operations seen anywhere in Africa for years. The rebels were tough, determined and tenacious as if they had long training for the assault.

This is perhaps the strongest evidence, although circumstantial, of foreign involvement in the latest Shaba Province troubles, although many local sources say they saw four white-skinned rebels speaking either Portuguese or Spanish during the six-day occuption.

They may have been Cubans or they may have been white Angolans of which there are many.

"I myself saw no Cubans," said Col. Philip Erulin. the French Foregin Legion commander whose troops recaptured the city Friday.

The Kolwezi invasion, code-named "Operation Dove," was entirely different in character from the 80-day Shaba war of a year ago when Zairian and Moroccan troops mostly shadow boxed with the rebels and hardly anyone was killed. In fact, it was snidly dubbed the "Pygmie and Coca-Cola war" by Western correspondents after Zaire used an American plane to fly in cases of the soft drink and committed a contingent of bow-and-arrow pygmie warriors to the fight.

Kolwezi shows not how far things have come from a year ago in the nature of warfare in southern Zaire, but also the seriousness of the problem that lies ahead for the 13-year-old government of President Mobutu Sese Seko. For Kolwezi and what it stands for is far from over.

Leaders of the mysterious National Front for the Liberation of the Congo are obviously determined to overthrow Mobutu and certain to try again and again. They have already dealt a Paralyzing blow to the bankrupt Zairian economy and had they held Kolwezi they would probably have declared a separate government and asked for recognition and aid from sympathetic African and Communist countries.

The full story of how the rebels organized their assault on this sprawing city of nearly 35,000, divided into two main European sections and five or six black African ones, may never be know. But the accounts of refugees and French and Belgain military sources here gives some idea of how it was done.

The main rebel striking force almost certainly came from camps inside Angola and had long, careful preparation in the assault of the town. The number of rebels who made the four-day trek across northwestern Zambia into southern Shaba Province is not clear. Hundreds of their supporters were already inside the city waiting to join those coming from Angola. Many Europeans said they or their servants recognized individual rebels as townspeople.

French military officials estimate that between 2,000 and 2,500 guerrillas took part in the attack. They had stockpiled vast quantities of arms before-hand in and around Kolwezi permitting them to cross Zambia dressed and looking like civilian refugees.

Most wore uniforms of one kind or another with the word "tiger" printed on arm bands. The followers of Patrice Lumumba, the leftist first premier of Zaire, called themselves "simbas," or lions after his assassination and their own rebellion in his name.

They carried a motley array of old and new arms - Soviet AK-47s, American M-16s, and Nato or Portugese FNs, as became clear from the 1,200 captured arms piled in front of the French Legion's headquarters at the Impala Hotel here.

Kolwezi was comparatively lightly defended at the time of the comparatively lightly defended at the time of the attack, with only two companies of soldiers - about 300 paratroopers - stationed there. Why no more troops were present when everyone knew something was being planned and soon to come remains unclear. Various African publications had been talking of the rebel buildup for several months. Portuguese-Speaking Invaders

The rebels themselves had infiltrated the city in large numbers at least a week before their assault and many Europeans told of seeing Portuguese-speaking Africans and strange faces in town. But no one seemed to take the signs of trouble for what they were.

The city fell to the rebels literally within hours of the first shots. The rebels also captured the strategic airport, where a dozen Zairian air force jets, helicopters and planes were knocked out, apparently with explosives, in expert fashion.

But the Zairian army held out in its headquarters and several smaller posts almost to the arrival of the first wave of Legionnaire paratroopers Friday afternoon.

The rebels knew exactly what they were doing. They hit all key points simultaneously making it virtually impossible for the Zairian troops to send reinforcements from one position to another. In any case, many of them simply fled into the bush. Well over 100 of the deserters appeared back in town after the arrival of the French.

As partial punishment for their behavior, the Zairian army deserters were taken to a villa where 34 European men. women and children were executed en masse in one room and shown the sight. Polite Commanders, Harsh Troops

The bahavior of the rebels varied greatly toward the 2,200 to 2,500 Europeans living in the city but it got progressively worse. The many rebel commanders and political commissars were extremely well disciplined and even polite in their dealings with the whites, but the conduct of their troops was a far different story.

Many Europeans told of how they had been robbed of food, watches, radios, tape recorders, cars and trucks. They said friends were shot down on the spot at the slighest sign of protest. It does not seem that rape or physical torture was widespread.

The rebels spent a lot of time trying to convince the local black population of the evils of the Mobutu government and the benefits of supporting the invading force. Some of their entreaties were purely financial - the promise of more money and better living conditions. One rebel showed a European servant an Angolan bill and said it was worth three times the Zairian equivalent.

Some of the attempted indocrination was more idelogical - denunciations of colonialism and imperialism. But it does seem that Marxism was the predominant theme at least in many conversations overheard by European refugees. These was some antiwhite progaganda tied to the better living conditions enjoyed by the Europeans but little outright racism. Rebel Support in Black Quarters

What took place in the heavily populated black African quarters of Kolwezi is less clear but some Europeans living there felt the rebels did not get the kind of popular support they had hoped for and that the antiwhite harangues were not appreciated. But the rebels found enough support there to infiltrate and live for a week without being betrayed.

The rebels' behavior took a sharp turn for the worse and a hatred for whites, particularly the French, became evident as news of the Legioniaires' approach reached the city by radio Wednesday. The last 48 hours saw indiscriminate killing all around the town of both whites and wealthy blacks associated either with the government or the big Zairian-Belgian mining company, Gecamines.

The death toll included more than 500 blacks, including rebels and residents of Kolwezi.

The latest white death toll, given out by the French government yesterday, is 200 with some estimates reaching 250. If this proves true, about one-tenth of the total white population was killed in the siege, a staggering proportion.

The whites have left now, however, and it is the blacks, 30,000 of them, who live today in the shadow of death and torture - now from the conquering and revenge seeking Zairian Army andits foregin supporters.