The Soviet Union, in a move that could have a major impact on the crisis-ridden economies of Eastern Europe, is planning to cut its energy exports to the region by 10 percent next year, senior Czechoslovak officials have confirmed.

The economic burden of Poland and growing domestic demands for energy have been cited as reasons for the Soviet action by Western economists here. They predict that, as a result, the Soviet Bloc countries will be forced to trim further their targets for economic growth during the present five-year plan.

Along with other members of the Soviet Bloc trading organization Comecon, Czechoslovakia has reacted to the cutback in supplies by drawing up a program of drastic energy savings. Additional imports of crude oil from Middle East producers for hard currency have been ruled out for economic and financial reasons.

At a meeting of the Czechoslovak Communist Party's Central Committee yesterday, party leaders warned that next year a 10 percent reduction in gasoline sales to motorists and a 17 percent saving in heating oil will be necessary. Factories have already been instructed to reduce consumption of light-oil products by between 12 and 13 percent.

Subsidized supplies of Soviet oil and other raw materials have been crucial to Eastern Europe's economic development. Any enforced cutback is therefore likely to cause considerable economic difficulties and, in the light of events in Poland, eventual political unrest as well.

Ever since the Soviet-led invasion of Czechoslovakia in 1968, political stability in the Soviet Bloc has been linked to steadily increasing living standards. But the era of high growth rates, underpinned by plentiful supplies of relatively cheap energy, now seems ended.

In the short term, East European leaders appear confident of their ability to impose austerity measures without an uncontrollable backlash of public anger. What has been described as "the Polish disease" will have little appeal as long as it is associated in the minds of ordinary citizens with shortages and economic chaos.

All the same, Soviet Bloc governments are making an extraordinary propaganda effort to convince the population of the need for sacrifice. Particularly in Czechoslovakia, officials have been much more frank in recent weeks about the scale of economic problems.

Unofficial reports of a cutback in Soviet energy supplies have been circulating in Eastern Europe during the past month. The reductions being discussed in bilateral trade talks vary from country to country, but are believed to average 10 percent.

In an interview today, a Czechoslovak government spokesman, Marcel Jansen, confirmed the reports. He was reluctant to go into details, but when asked about speculation of a 10 percent reduction, he replied: "I think this figure is close to reality."

Western economists here have suggested that, in Czechoslovakia's case, Soviet oil imports are likely to be reduced by 2 million tons from 19 million this year. This figure corresponds to the enforced savings in heating oil and gasoline outlined by the planning minister, Svatopluk Potac, in his address to the Central Committee this week.

Energy supplies are further complicated by the sharp drop in coal exports from Poland which, according to one Czechoslovak official, are down more than 60 percent this year. Last month it was revealed that supplies of electricity from Romania, which account for around 10 percent of Czechoslovakia's energy imports, had also been halted temporarily.

Soviet oil supplies to Czechoslovakia had doubled over the past decade. Prices increased fivefold -- but are still well below those OPEC charges.

The energy crisis is forcing Czechoslovak leaders to come to terms with the inefficiency of their economy. According to official figures, Czechoslovak factories use as much as 50 percent more energy than Western factories to produce the same product.

So far, however, there has been no criticism of the central planning mechanism around which the economy revolves. Instead, the remedy is sought in increased workers' productivity, less waste and streamlined management.

A senior Western diplomat here with experience of the Soviet Union pointed out that Moscow was faced with the cost of grain imports from the West, interest payments on its hard-currency debt, and increased financial and economic assistance to Poland.

"This is yet another indication that the Soviet Union's ability to throw money away for political purposes is becoming ever more limited. They tend to put politics first, but this seems to be a victory of economics over ideology," he said.

The uncertainties over energy supplies have seriously complicated planning in Eastern Europe. Czechoslovak officials say the economy is unlikely to grow at all next year -- and certainly will not reach the already scaled-down target of 3.4 to 3.7 percent in its five-year plan.

Other Comecon countries have already cut their planned growth to the lowest levels since the communist takeover of Eastern Europe after World War II. Average growth rates, which exceeded 7 percent per year in the early 1970s, fell to 3.3 percent in 1980 and are likely to drop still further in 1981 and 1982.