Eastern Europe, which for years ridiculed the energy crisis an an exclusively capitalist phenomenon, is now finding itself hard hit by the world fuel shortage, with some countries facing severe economic cutbacks.

Fuel rationing, restrictions on outside lighting and gasoline prices reaching $4.25 a gallon are measures that indicate the seriousness with which the Communist governments of Eastern Europe are now taking the crisis.

The problem of long-term energy supplies dominated last month's meeting of Soviet Bloc prime ministers in Moscow. Faced with a drop in its own oil output, the Soviet Union has made it clear to its allies that it cannot guarantee their full fuel needs in the future and they will have to look elsewhere.

While the Soviet Union was once Eastern Europe's exclusive supplier of crude oil, it is expected to provide only about 75 percent in 1980 and 50 percent by 2000. Meanwhile, its prices are based on a five-year moving average of the world price.

Thus, Western experts expect that last month's increase in oil prices set by the Organization of Petroleum Exporting Countries will mean at least a 9 percent increase in the price of Soviet oil to Eastern Europe.

This has already had a jarring effect. Gasoline prices in Bulgaria, the Kremlin's closest ally, have been doubled, to $4.25 a gallon, spawning some black humor among the country's hardpressed band of private motorists.

The latest joke goes like this:

According to a government decree, special teams of doctors and policemen are to be sent to every gas station in the country. The doctor's presence is required when the motorist finds out what the new prices are. If he recovers from the shock and still manages to pay the bill, the policeman is responsible for investigating where he got hold of so much money.

Of all the nations of Eastern Europe, Bulgaria is most reliant for its energy supplies on the Kremlin. It has had to ban street lighting after 11 p.m. and ration home heating fuel. But, in different ways, the rest of the Soviet Bloc is also feeling the effects of the worldwide energy shortage.

The Soviet Block economic grouping Comecon plans to tackle the long-term problem of energy supplies by switching to nuclear energy and introducting new energy-saving technology.

That, however, leaves East European countries faced with the immediate choice either of importing oil at inflated world prices for scarce foreign currency or of doing without.

At the Moscow summit, Czechoslovak Prime Minister Lubomir Strougal said energy shortages had forced his country to reduce its targets for both the present and future five-year plans. The Czechoslovak economy, he said would develop at a lower rate.

The only East European country to succeed in increasing imports of Soviet oil is Hungary, which has to pay for the extra supplies in Western currency at world prices.

The Hungarian press adopted a particularly critical attitude toward the recent OPEC price increases, describing them as "irresponsible" because of their destabilizing effect on the world economy.

Even more seriously hit is Romania, the only country in the block that imports no oil from the Soviet Union. Once self-sufficient in energy, Romania announced in March that it now imports more oil than it produces. Since then supplies have been drastically reduced as a result of the revolution in Iran.

Romanian President Nicolae Ceausescu, known for his independent foreign policy stance, has spent the last few months trying to tap new energy sources in Africa and the Middle East, without much apparent success. He has indicated he would like to purchase oil from Moscow but would not accept the conditions of political dependence that would probably accompany such a deal.

Romania increased its gasoline prices 40 percent last month and introduced other energy-saving measures such as summer time. Last week Ceausescu announced that the country would restructure its long-term industrial development with operations using large amounts of fuel eliminated or cut back.

For communist but nonaligned Yugoslavia, the problem is not so much finding supplies of oil but paying for them. Yugoslavia gets most of its oil from Iraq, which recently agreed to guarantee supplies on a long-term basis, but the $1.5 billion bill is a heavy strain on the country's balance of payments.

Yugloslavia is the only East European country where public opposition to the government's energy-saving plans is tolerated.

Recently the inhabitants of the coastal resort of Zadar blocked plans to build a nuclear power station in their district on environmental grounds. The plant will now be built elsewhere.

Meanwhile, isolationist Albania which broke away from the Soviet Bloc in 1962, has launched a bitter attack, accusing the Soviet Union of exploiting the energy crisis "to force its vassal countries to pay ever more dearly for their fuel."

Just how Albania is solving its energy problems, without foreign suppliers and very limited domestic production, remains a mystery. It is only partly explained by the fact that, unlike the rest of Eastern Europe where car ownership is steadily increasing, in Albania private cars do not exist.