The $25 billion Soviet natural gas pipeline, a project opposed by the Reagan administration, is destined to benefit not only European consumers but also major multinational oil companies, including U.S.-based Exxon, which have signed up for large volumes of the gas under agreements reached with the Soviets.

While administration officials have vowed to block or delay construction of the controversial pipeline, Exxon, Shell of the Netherlands and Britain's BP are busily planning to add their share of the new Soviet gas to the pool they use to supply industries and homes in West Germany. The stake of the oil multinationals in the pipeline project adds a new dimension to the unresolved tensions within the Reagan administration on this issue.

The administration has a basic pro-business inclination; it also is determined to stand up to the Soviets in the wake of the crisis in Poland. The two aspects of its policy are at war.

U.S. officials warn that the pipeline, the largest single East-West business deal in history, will drastically increase European dependence on Soviet energy and will provide Moscow with $10 billion a year in hard currency.

But the companies argue that the 40 billion cubic meters of natural gas a year from the West Siberian fields on the Yamal Peninsula, due to begin flowing in 1984, are needed to supplement new reserves in the North Sea as well as old ones in the Netherlands that are expected to decline sharply in the next decade.

"Reagan has absolutely no reason to forbid this business," said Wolfgang Oehme, chairman of Exxon's Hamburg-based German subsidiary, in the current issue of Der Spiegel magazine.

"We are working within the framework of a German government assessment that this project is good for Germany," said an Exxon spokesman in New York City. "It's not a question of whether we support or don't support the project. It's a question of our companies operating according to the desires of local government."

Mobil appears to be the only major oil company operating in West Germany opposed to the deal. Officials of that company have declared that the pipeline is not necessary and have said that its completion will undermine Mobil's efforts to develop non-Soviet natural gas reserves in the North Sea and West Africa.

The pipeline deal has become a major political issue in the Atlantic alliance. European governments look to the project to provide business and jobs for local firms in the short run and new energy supplies later. U.S. officials, aware that an all-out effort to block the project could split the alliance, are nevertheless considering new steps to delay it.

On Dec. 30, President Reagan revealed a list of economic sanctions against the Soviet Union in retaliation for the imposition of martial law in Poland. He indicated that there could be no "business as usual" with the Russians as long as the repression continued.

The list covered U.S. companies with contracts to export pipeline equipment to the Soviet Union, such as General Electric and Caterpillar, but exempted grain shipments and made no mention of the oil companies' role in the gas deal.

Since then, however, events have been driving home the problems involved in using economic measures to achieve political objectives in a highly interdependent international economy dominated by the activity of multinational corporations.

West European firms with lucrative contracts to supply pipeline equipment have indicated they will try to go ahead with these sales despite Washington's restrictions.

European banks are continuing with plans to finance the project, and on Jan. 23 France's state-owned Gaz de France signed a 25-year natural gas contract with the Soviets that will make the country dependent on Russia for a third of its imported gas needs.

On Feb. 15 the supervisory board of Ruhrgas, a huge West German utility in which the oil multinationals have a 65 percent equity interest, is expected to give final approval to the Soviet gas deal that will provide the country with 10.5 billion cubic feet a year starting in 1984.

Ruhrgas has signed up for half of the new gas. Another quarter of it will go to a company called Brigitta, jointly owned by Exxon and Shell. Two other companies, Thyssengas and Gelsenberg, will each get 10 percent.

Exxon and Shell each have a 25 percent interest in Thyssengas, while Gelsenberg is wholly owned by BP. The remaining 5 percent is earmarked for small German companies.

The West German government, backed by leading industrialists, is strongly supporting the Soviet gas purchase with the proviso that the nation's dependence on Soviet gas go no higher than 30 percent of Germany's total supply. This allows for substantial growth in the Soviet share of the German natural gas market, now only about 11 percent.

One of the strongest backers of the East-West trade ties is industrialist Otto Wolff von Amerongen, head of the West German chamber of commerce and a member of Exxon's board of directors.

Mannesmann, the huge West German steel company that has a contract to supply wide-diameter pipe for the Siberian gas line, owns a 7 percent interest in Ruhrgas, the largest German gas purchaser.

Italy, Austria, the Netherlands, Belgium and Switzerland are expected to follow up the French and West German lead with gas purchase deals of their own. France, Italy and Austria import gas through state companies. But Exxon and Shell are members of consortiums that import gas on behalf of the Netherlands and Belgium.

Senior administration officials are aware that U.S. multinationals are deeply involved in the West European natural gas industry but say they see no way, at this point, to apply pressure on the companies to line up behind the Reagan policy.

The multinationals already take some of the 25 billion cubic meters of gas the Soviets sell to Western Europe.

MEGAL, the major pipeline transporting Soviet gas from the Czechoslovak border to the West, is jointly owned by Ruhrgas and the French national gas company.

Exxon and Shell each own 30 percent of the huge Groningen field, Europe's largest natural gas resource.

The two companies together also have a half interest in Gasunie, the company that exports Groningen gas and distributes it within Holland.

Together, Exxon, Shell, Mobil and Texaco produce 81 percent of West Germany's natural gas. Exxon and Shell also have interests in north-south pipelines that carry North Sea and Dutch gas across West Germany to Italy.

Administration officials say that this system is now being redirected toward major dependence on the Soviet Union without adequate study of the feasibility of alternatives such as U.S. coal or accelerated use of the vast North Sea reserves.

At the same time, the Washington, D.C., consumer group Energy Action has charged that the multinationals are using the Soviet purchase deal to set a world floor price on natural gas linked to oil prices that eventually could mean higher U.S. fuel prices.