Brussels — NATO allies have told France they are concerned that Western security secrets might leak into Communist hands now that four members of the Communist Party sit on the French Cabinet.
But privately, officials in Britain and other Western European countries say they believe President Mitterrand will take steps to retain allied confidence by holding such secrets closely within the Elysee Palace.
Officials in a number of countries contacted by this newspaper June 24 admitted their concern. But they tended to take their cue from West German Chancellor Helmut Schmidt's calm public comment that "I do not think one should dramatize" the arrival of Communist ministers in Paris.
A typical reaction came from one well-placed European diplomat stationed here in this crossroads of Europe:
"We don't welcome Communists in the French government," he said in an interview. "We see it as a domestic political maneuver by Mitterrand. It might be a dangerous one, but it is also clever.
"Mitterrand wants to hold the Communists hostage, as it were, so that they can't critize him openly between now and the municipal elections in two years' time -- elections highly important in French politics.
"After that, Mitterrand may well ditch the Communist Cabinet members: And the Communist Party itself may want to regain its freedom of action by leaving the government.
"My government has asked the French about security for sensitive information from now on, and the French have assured us all such information will be held intact and away from Communist eyes."
A number of diplomats contacted said their capitals had asked the French directly about security.
One factor easing their fears was the French presidential style of government. Foreign policy and defense matters are decided largely by the president himself with only a few senior Cabinet ministers. There is no tradition of collective responsibility for all Cabinet members.
The four Communist Cabinet ministers in France hold the portfolios of transport, health, administrative reforms, and vocational training.
Transport seems to be potentially the most sensitive, but even there allied diplomats think Mitterrand has no choice but to cut Transport Minister Charles Fiterman out of sensitive discussions and paper work.
In Britain, the left-of-center Guardian newspaper remarked that the Communists had had to make "all the concessions" in the joint policy agreement hammered out with the Socialists before the Cabinet was announced.
The Communist Party said it accepted the Socialist positions on foreign policy in particular -- opposition to the Soviet invasion of Afghanistan, support for French participation in NATO's nonmilitary aspects, and other stands opposed to the Moscow view of the world.
Conservative Europeans don't trust the Communists' word. They think Moscow will try as hard as it can in private to extract whatever information the Communist ministers come across.
A spokesman for NATO in Brussels would not comment publicly on a "French internal matter." Privately, NATO secretariat officials said European countries were more accustomed to active Communist parties than the United States was, and tended to react more moderately to the French move.
According to one report, Paris has assured NATO headquarters in private it will take all responsibility for safeguarding alliance intelligence.
British officials in London denied a London Times report that Britain felt "deep misgivings" about the Communist ministers. But they added that the presence of the ministers raised "practical questions" about confidentiality and that these would be discussed with Paris.
Lord Carrington, British foreign secretary, discussed the new French Cabinet with Vice-President George Bush, who arrived in London for talks June 24 straight from a session with Mr. Mitterrand. Bush expressed US "conc ern" at the new Cabinet.