Former president Valery Giscard d'Estaing today implicitly criticized France's refusal to grant overflight rights to U.S. planes for the bombing mission against Libya by calling for "proof" of western solidarity against terrorism.

The former president's statement coincided with calls by several other right-wing deputies in the National Assembly for tougher action by France and other Western European countries against Libya. Criticism of the U.S. action in attacking Libya has been relatively muted here in contrast to West Germany and Britain.

French political commentators interpreted the refusal to grant the United States overflight rights as a consequence of France's traditional reluctance to get dragged into overseas "military adventures" over which it has no control. This was one reason why Gen. Charles de Gaulle withdrew France from the integrated military command of the North Atlantic Treaty Organization in 1966.

The French decision, which meant that British-based F111 aircraft had to fly 2,400 miles out of their way, reportedly was linked to delicate negotiations over the fate of French hostages held by Shiite Moslem extremists in Lebanon. Officials reported today receiving handwritten letters from four of the hostages, members of a French television crew.

Conservative Prime Minister Jacques Chirac, who made the decision jointly with Socialist President Francois Mitterrand, heads the neo-Gaullist Rally for the Republic party, which is in coalition with the center-right Union for French Democracy (UDF) founded by Giscard.

During today's question period in the National Assembly, Gaullist deputies generally supported the government's position, while UDF politicians criticized the lack of West European support for the United States.

In his statement today, Giscard said that he approved U.S. action against Libya, describing it as "justified by the repeated acts of aggression against the populations of the western democracies." He added that, at times of tension caused by international terrorism, "The West must above all give proof of its solidarity."

The former president compared the U.S. bombing of Libya to France's intervention in the African nation of Zaire in 1978 following an insurrection in Kolwezi. He noted that, on that occasion, the United States had provided military planes to transport French forces from Corsica to Zaire.