Hundreds of French Foreign Legion paratroopers were dropped on the besieged mining center of Kolwezi in southern Zaire yesterday in a daring bid to free up to 2,000 Europeans being held hostage by rebel forces there.

As the Legionnaires engaged the rebels in sharp clashes while fighting their way into the town, there were reports of rebel executions of foreign hostages. The official Zairian News Agency said the bodies of 44 Europeans shot in the morning had been discovered by the French paratroopers. Their nationalities were not immediately known, and there was no further confirmations of the incident. The French Defense Ministry confirmed the deaths late yesterday.

[In Brussels, Belgian Prime Minister Leo Tindemans announced that Belgian paratroopers were on their way to Kolwezi to join the operation. He said the Belgian forces had left Kamina, 140 miles to the north, and that if everything went according to plan, the first evacuees would reach Brussels tonight.]

Between 600 and 1,000 French Legionnaires were reported involved in the airdrop in and around Kolwezi, while the Belgians were arriving in Kamina.

By late in the afternoon, reports reaching here said the French had captured four rebels after knocking out an armored car apparently captured from the Zairian Army earlier. Some Zairians and Europeans were reported leaving their homes for the first time since the siege began eight days ago.

In Washington, White House Press Secretary Jody Powell said U.S. assistance involved a total of 18 planes flown by American crews. The planes, he said, were used to carry ammunition, fuel, trucks and French drivers to areas in Zaire "outside the area of conflict."

[Powell said that up to a dozen U.S. military personnel would be working on the ground at Kamina airfield to unload fuel and provide communications.]

[But President Carter stressed that "we have a very limited role to play" in Zaire.]

The last such operation of this kind took place in November, 1964, also in Zaire, when American planes dropped four or five companies of Belgian paratroopers on Kisangani, then known as Stanleyville, to rescue whites being held by the leftist rebels. A small number of the white hostages died in the course of the action, and there were fears here that this could easily happen again in Kolwezi.

Reports available here said that altogether about 2,700 French and Belgian paratroopers were taking part in or backing up the operation - the largest such rescue mission ever undertaken by Western nations on the African continent in recent times.

The Zairian News Agency said a motorized Cuban infantry company was spotted fighting on the rebel side but it retreated with the arrival of the French paratroopers. There was no independent confirmation of this. The report said the Cubans were clearly identifiable among the Katangese rebels.

(In Paris, a French Defense Ministry official said that French reconnaissance units had spotted the withdrawal of a column of Cuban and Soviet military advisers about 36 hours after the Foreign Legion operation began.

(The official said that the French were concerned that with the departure of the foreign advisers, the rebels' discipline would break down. No other French ministry officials made the same assertion about the presence of Cuban or Soviety advisers, however.)

There were few details immediately available on the military situation inside Kolwezi or on the fate of the Europeans caught there in the fighting. Western correspondents who flew into Kolwezi Airport on Thursday afternoon with Zairian President Mobutu Sese Seko could hear fighting under way nearby.The press party stayed only 20 minutes before departing hurriedly again for Kinsahsa.

It appeared from their accounts that the Zairian paratroopers who dropped into the Kolwezi area Tuesday had gained a tenuous hold over the airport, but that the rebels were holding most of the town and were still threatening the airfield.

The Zairian government said that its troops had taken back not only the airport but also several strategic points inside the town, and that the tide of battle was turning in its favor.

It also announced that President Mobutu had decided to recall Zaire's ambassador to Moscow because of alleged Soviet involvement in the latest Shaba rebellion and that it had informed the United Nations of further evidence of neigboring Angola's support for it.

A statement issued by the Zairian News Agency said radio signals from the rebel's headquarters in Chicago inside Angola had been intercepted and that rebel leader Nathaniel Mbumba had ordered his guerrillas to massacre all white hostages in Kolwezi before retreating back to Angola through Zambia.

Mbumba also told his forces to destroy the Gecamines mining facilities, the big Belgian-Zairian company operating in Kolwezi, and to bring back all youths they could seize before abandoning the town, the statement said.

In addition to assailing the Soviet Union, Cuba and Angola for their backing of the Shaba rebels, the Zairian government has accused Algeria of training the Katangese gendarmes with the help of Libya. Shaba province was formerly known as Katanga.

Apart from the Zaire News Agency assertion, there have been reports that at least nine and perhaps as many as 20 Europeans have either been killed in the fighting or executed by the rebels. But the precise conditions in which the whites are being held are not known here. Nor is it known whether all or just some males are actually rebel hostages.

One breakdown of the hostages by nationalities was made available. It gave these figures: 1,250 Belgians: 450 to 500 French: 100 Portuguese: 21 Britons: 19 Swiss: 14 Americans; eight West Germans and two New Zealanders.

Kinshasa's International Airport was abuzz yesterday with activity as French civilian and military aircraft unloaded and reloaded paratroopers destined for Kolwezi. One big Zairian C130 an DC10 were also being loaded with troops and supplies heading for the war zone.

French legionnaires began arriving at the airport early yesterday on French civilian Boeing 707s, as well as Transall military transports. They carried maps of Kolwezi with red crosses marked mostly around the airport, suggesting that this was their principal target.

They also had instructions on how to deal with the local population and any bodies they might come across. They were warned to look out for booby traps.

The legionnaires, 75 per cent of whom are not French nationals and most of whom are Germans, appeared in high spirits and anxious to get on with the operation after an all night flight from the Mediterranean island of Corsica.

There was considerable speculation here that the French and Belgian paratroopers might be used to crush the rebel forces holding both Kolwezi and the railroad town of Mutshatsha 60 miles to the west, although the two governments have been stressing the purely humanitarian nature of their mission.

When Belgian paratroopers were used in the 1964 drop on Stanleyville, they also brought to an end the leftist rebel forces holding both Kolwezi lished there. This helped to clear the way for President Mobutu's rise to power over a united Zaire one year later.

Agence France-Presse reported that the British Air Force planes with European refugees from Zaire on board touched down at Porto Santo in Madeira.

The planes were taking part in a British-organized airlift to fly European refugees from the fighting in Zaire to London, a British Embassy spokesman said. The spokesman said the operation was intended only to help the refugees, and had been organized with the Zambian goverment's approval.

Washington Post staff correspondent Ronald Koven reported from Paris:

French Defense Ministry spokesman Pierre Saulier said the Foreign Legion paratroopers were advancing slowly house-to-house and were encountering heavy resistance. He said the Legionnaires so far had destroyed two light tanks.

This description of the fighting contrasted sharply with reports by the Zaire News Agency and the South African radio that the French troops had met little resistance and were already in control of most of Kolwezi.

The Defense Ministry spokesman said the Legionnaires had already found the bodies of some of the victims of the reported massacre. A French presidential palace official spoke of dozens dead.

The French officials stressed that their forces were able to arrive in the war zone faster than the Belgians because the French Transall troop transport planes are faster than the American-made Hercules C130 transports being used by the Belgians.