PARIS, SEPT. 30 -- As Germany prepares to celebrate union on Wednesday, its neighbors in the European Community are becoming pessimistic about achieving early progress toward the long-planned economic and political integration of their region that would bind the new Germany to the West.

Momentum toward a United States of Europe, achieved during the economic boom of the last five years, is waning as nations confront a recession caused by soaring oil prices, a possible American banking crisis and the costly bailout of Eastern Europe.

European states have consulted frequently over the Persian Gulf crisis since Iraq's occupation of Kuwait showed the vulnerability of their oil supplies. But no plausible plan has emerged for a joint European military force that could respond to similar threats in the future.

Last year's euphoria over the collapse of the Iron Curtain and a new Europe without frontiers is giving way to fresh anxiety about future waves of economic refugees overwhelming affluent societies in the West.

Germany is considering how to restrict an influx of Poles, having already tightened visas, and West German officials have predicted that as many as 3 million Soviets with German links could start to head west when the Soviets lift visa restrictions.

France, Italy and Spain also want to erect new barriers to thwart a rising immigration from North Africa.

The confluence of these economic and social challenges at the historic milestone of German unity could turn out to be too much of a burden for Europe to absorb while pushing ahead with integration. Just as in 1973, when European ambitions for greater political and economic unity fell apart when confronted by the first oil crisis, a shortsighted scramble to protect national interests could unravel the considerable gains toward West European unity in recent years.

In France, Belgium, the Netherlands and Italy, officials questioned about the impact of German unity said they were convinced that a bigger, stronger Germany would remain firmly wedded to democratic values and the prosperous trading ties that the world's biggest exporter has cultivated among its West European partners.

But the officials said they expected two important changes: First, a much greater German interest in relations with the Soviet Union and other East European neighbors, not for commercial reasons but because continuing political instability in those countries would affect German interests; second, a stronger national and cultural identity could make German politicians less amenable to sacrificing national interests in favor of larger European goals.

"The real danger for European unity is that Germany will become so concerned about economic and political turmoil in the East that it will not be able or willing to cede control to European institutions," observed a senior French diplomat. "What German politician will tell voters, 'Now that the German people have regained their sovereignty it is necessary to give it away'?"

German reticence about surrendering control of political or economic destiny is already evident in the reservations expressed by its financial leaders -- notably Bundesbank President Karl Otto Poehl -- on moving ahead with the next phase of economic and monetary union on Jan. 1, 1993. Poehl insists that the huge costs of his country's unification are too burdensome for Germany to risk the uncertainties of plunging ahead to create a common European currency.

While Foreign Minister Hans-Dietrich Genscher favors a pro-European response, German Chancellor Helmut Kohl has refused to give any assurances and is not likely to do so until all-German elections are held. His concern about being depicted as ceding too much of German sovereignty indicates European unity could become a major German election issue.

Meanwhile, exasperation with German ambivalence toward Europe is growing more angry. "What do the Germans really want, I keep asking myself," said Jacques Delors, president of the European Community's executive commission, at a seminar here last week. "We need clear and unambiguous commitments from them to achieve an acceleration of European unity. Otherwise, we will end up with a weak and flabby Europe and a powerful Germany in the middle."

The new uncertainties have arisen only months after EC leaders agreed that German unity should be exploited to propel greater European integration. After some hesitation, French President Francois Mitterrand and other European leaders gave their blessing to a rapid fusion of the two German states after the Berlin Wall was breached last November.

But Mitterrand linked his assent with an appeal, backed by Kohl, that West European leaders hold twin conferences this December to endorse a timetable for creating a common European currency and transferring political power to supranational institutions.

Less than three months before the Rome meetings, diplomats preparing the sessions say a fiasco is looming because conflicting national interests are paralyzing any progress.

Worried about the costs of unification, Germany is nervous about jettisoning its stable mark in favor of a pan-European currency. France is reluctant to turn legislative powers over to the European Parliament. And British Prime Minister Margaret Thatcher, suspicious as ever about European integration, wants to fling the community's doors open to East European countries and douse any hopes of cohesive political unity.

"No matter what we decide to do, Germany holds the key to the future of Europe," a top French official said. "It will determine whether there will be a resurgence of nationalism, or whether we move on to a new level of European cooperation."