The United States recently warned its Western European allies about the dangers of increased energy dependency on the Soviet Union as intensive negotiations proceed for Western construction of a multibillion-dollar Soviet pipeline that would double gas deliveries to Western Europe.

U.S. sources said the American comments to the Europeans within the last few weeks conceded in advance that Washington recognizes the European need to diversify its energy sources. The Carter administration even authorized the Caterpillar Tractor Co. to bid on supply of pipe-laying equipment for the project.

U.S. diplomats have nevertheless been urging the Europeans to try to build alternatives to Soviet gas into their planning. The Americans are understood to have told the West Germans, French, Italians and Belgians, who would receive the Soviet gas that they should also seek "surge capacity" from friendly countries such as the Netherlands and Norway in case of a Soviet cutoff.

The French and West Germans reply that the Soviets have always been reliable suppliers and that present proposals envisage a total West European dependency on Soviet energy of 5 per cent at most.

The Soviets have already clearly indicated, however, that they would like to wean Western Europe away from its partnership in energy matters with North America toward a more "natural" energy alliance with the Soviet Union. Soviet leader Leonid Brezhnev has been pressing for some time for a pan-European energy conference as a followup to the Helsinki accords of 1975 on detente in Europe.

Soviet central committeeman Nicolai Portugalov wrote two major commentaries for the Soviet news agency Tass in February alluding to the community of interests in energy problems between the Soviets and West Europeans, as opposed to U.S. actions that he said risked a conflagration in the vital Persian Gulf oil region.

Since then, the Soviets have been trying to demonstrate the practicality of this appeal to Western Europe in a number of ways, starting with the natural gas negotiations to double deliveries from 25 billion cubic meters yearly by 1986.

Other Soviet moves have included providing some of the energy statistics the West has been demanding as a precondition to holding an energy conference and increased technical contacts such as a high-level Franco-Soviet energy colloquium in Moscow last week.

While West German Chancellor Helmut Schmidt and French President Valery Giscard d'Estaing have written Brezhnev accepting in principle the idea of an East-West energy conference, West European analysts recognize a number of problems with current Soviet energy proposals and potential pitfalls with longer term projects.

Perhaps the greatest obstacle is the need for the Soviets to deal first with the energy needs of Eastern Europe as a lever to retain political control before diverting much larger amounts of energy exports to Western Europe.

Western analysts say that one of Moscow's objectives at an East-West energy conference would apparently be to get Western recognition of the Soviet position as Eastern spokesman for bloc-to-bloc arrangements, curbing the current freedom of Poland, for example, to make bilateral deals with France for Polish coal.

The gas negotiations are said to be stuck over Soviet demands that the West in effect finance the 3,000-mile pipeline from Yamal Peninsula to Western Europe by providing the $10 billion to $15 billion worth of specialized piping and equipment at what is by current standards a giveaway interest rate of 7 to 8 percent, instead of the market level of 10 to 11 percent.

The Soviets are asking Western companies to take payment in natural gas, presumably at prevailing international prices, when the pipeline is completed in five years. Another drawback is that the Soviets are seeking Western oil-prospecting and drilling technology as a sweetener in any deal they make, something the West has long hesitated to provide.

The state of Soviet technology for extracting oil from the permafrost of northwestern Siberia, deep-well drilling generally and offshore in proven underwater oil regions such as the Barents Sea in the Arctic Ocean near Scandinavia is the Soviet Union's Achilles' heel in energy development. But the Soviets have so far been unwilling to allow Western technicians to accompany the delicate and complicated equipment into strategic regions.

Authoritative Westerners have concluded that the Soviets do not want outsiders to see firsthand that the key oil region is an enforced labor center where regular workers cannot be attracted to the uncomfortable conditions, even at double or triple normal wages.

Unlike past energy deals with the West, the Soviets are now trying to play Western companies and banks against each other by refusing to deal with consortium bidding for all the pipeline. Instead, the Soviets have broken the project up into segments for separate bidding.

The argument about excessive dependency on Soviet energy supplies in the West apparently has its mirror image on the Soviet side. Some Western sources note evidence that Soviet technicians and economists argue for the advantages of Western technology, while security and political officials argue about the dangers of depending on Western personnel and techniques.

Another mirror-image argument has apparently been settled in favor of more realistic domestic pricing of energy.Soviet consumers have been getting their home gas and electricity at token prices.

Soviet economists have argued that such unrealistically low prices not only encourage waste but also make many energy extraction projects seem unprofitable when judged by the income they generate domestically. Energy projects with major export possibilities are easier to sell to Soviet central planners since they are greatest source of Soviet hard-currency earnings.

The Swedish firm Petrostudies, widely viewed in Western oil circles as an unofficial conduit for Soviet petroleum data to the West, recently has issued a report saying that Moscow plans to start charging internal consumers more realistic prices. West European observers greet this as the kind of stimulus to Soviet energy development that they say should help Moscow belie excessively pessimistic U.S. official views of Soviet potential contained in published CIA studies.

Even the most optimistic West Europeans are having trouble accepting Moscow's official predictions of sustained high petroleum production through the end of the century. West European analysts note that Soviet statistics supplied in response to Western demands for more data lump together natural gas and petroleum prospects. This, the analysts conclude, simply is a way to cover up the expected decline in petroleum production that the Soviets plan to make up for by producing more gas.

"There is no question," said a French energy official, "that the Soviet Union has a great energy future. It is in gas."

When challenged about the dangers of dependency on that gas, such officials answer that they would welcome nothing more than U.S. pressure on countries such as Norway to provide at least the possibility of an alternative supply in an emergency. But, said one European official, the Norwegians are harder to deal with than the Soviets or the Arabs.

"We don't expect any help from them," he said.