French military transport planes began landing Moroccan arms in the heart of Zaire's embattled copper belt today as a major political dispute flared in Paris over France's decision to help the Zaire government put down the five-week-old invasion.

French Communists demanded an immediate halt to the airlift and warned that it was unconstitutional and could involve France in a "dangerous" conflict. They called for a parliamentary debate on the move.

Some French Socialists and Paris newspapers joined in denouncing the operation, but government supporters defended it as "aimed at safeguarding Zaire's independence."

(In Washington, State Department spokesman Hodding Carter said the French decisin to assist the Zaire government "underscores the seriousness of the situation and the need for a solution to be found."

(Carter said there had been no prior planning between France and the United States, but that President Valery Giscard d'Estaing's government had informed Washington of its intentions. He added that under international law, "France has the right to support" Zaire after receiving a request for assistance.)

The French airlift, announced yesterday, involves 11 millitary transport planes and their French crews.

According to numerous sources here, in Morocco and in France, the planes have begun landing war material in Lubumbashi, formerly Elizabethville, the capital of Shaba Province, formerly Katanga. The province was invaded March 7 by Katangan rebels from adjoining Angola, and the rebels now control several towns in the province.

A news blackout continued from the battle zone, 900 miles south of Kinshasa, but sources close to the Moroccan government said in Rabat that 1,500 Moroccan troops have been flown to the area and another 1,500 are on standby to be airlifted to Zaire if necessary.

The rebels were last reported in possession of several towns captured without much of a fight at the beginning of the invasion and were reported headed toward Kolwezi, a major center of the copper industry.[TEXT ILLEGIBLE] ambassador, plans Tuesday to go on television to explain the airlift.

Gaullist leader and former Prime Minister Maurice Cove de Murville said today the president acted to reassure French-speaking African states worried by developments in Angola, where Soviet-armed Cuban troops helped the Popular Movement for the Liberation of Angola to victory in last year's civil war.

The independent newspaper Le Monde said the airlift amounted to military intervention and risked losing France much support and understanding "for a doubtful gain."

The conservative L'Aurore, however, headlined its commentary "France Shows the Way." It said that "as the big Western powers appear resigned to accepting black Africa's drift toward the East, France is setting the example for Western presence on the continent."

The Communist floor leader in the National Assembly, Robert Ballanger, charged in a letter to Giscard that the decision to furnish aircraft "involved France in the mechanics of a colonial war."

"You have not hesitated to violate the constitution," Ballanger said.

He demanded an immediate halt to the airlift and called for an urgent debate on the "dangerous decision."