Last week, Czechoslovak police rounded up 11 prominent human rights activists including Jiri Hajek, foreign minister under Alexander Dubcek during the "Prague Spring." The dissidents, who had signed a letter of support for the Polish strikers, were held for 48 hours and then released.

A minor incident perhaps, but an illustration of the nervousness that has seized many East European capitals in the wake of the long summer of labor unrest in Poland. Like Communist Party leaderships elsewhere in the region, the Czechoslovak authorities are anxious to demonstrate their readiness to take firm action to prevent the Polish initiative from spreading. r

The Polish crisis is not yet over. Many Western analysts believe that the Kremlin is likely to exert considerable pressure on the Polish leadership to withdraw the unprecedented concessions granted to the striking workers, particularly the establishment of independent trade unions. Given the present mood of the Polish people, it is difficult to see how such an attempted rollback could succeed without provoking even more serious strikes.

But whatever the final outcome, it is safe to predict that 1980 will prove to be a watershed in the troubled postwar history of Eastern Europe -- a highly visible stage in the slow decay of the Soviet empire.

After World War II, Stalin attempted to guarantee Soviet security by creating satellite states bound together by Marxist-Leninist doctrine. Suspicious of equal partners, he demanded strict obedience and the duplication of the Soviet system under quite different conditions.

The result has been a superficial stability broken by a series of crises: the breakaway of Yugoslavia in 1948, the crushing of the Hungarian revolution in 1956 and the invasion of Czechoslovakia in 1968.

Since Stalin's death, the basis of Soviet dominance over Eastern Europe has undergone a profound transformation, partly as a result of these crises. The Kremlin now relies more on economic cooperation than brute repression to keep its allies under control. But the contradictions are still present -- and they surfaced again in Poland this summer.

Ironically, a convincing Marxist explanation can be advanced for the strikes in Poland. After 35 years of socialism, the centrally planned economic system has become outdated and no longer able to cope with the demands of a modern society.

This point was made by one of Poland's most distinguished journalists, Mieczyslaw Rakowski, who said in a recent speech that the system introduced in Poland after the war was modeled "on the way the Soviet Union, which has quite different traditions, was run in the 1930s."

The same argument applies in varying degrees throughout the Soviet Bloc. So far the accepted wisdom is that, without a change of policy in Moscow first, there can be no radical changes in individual countries. The Kremlin's attitude toward Poland will be watched closely throughout Eastern Europe to see if this theory still holds true in today's vastly more complicated economic climate.

The long-term impact of the Polish crisis on Eastern Europe is likely to be enormous. But it will also be a good deal more complicated than the straightforward copying of the Polish example.

In many ways, Poland is unique -- as Polish diplomats have been trying to get across to their worried Soviet Bloc colleagues the last few weeks. No other communist leadership has to deal with Poland's brittle combination of an alternative power center in the form of the Roman Catholic Church and deep historical antagonism toward Russia.

Furthermore, although all East European countries face serious economic problems, none is in such dire straits as Poland -- which registered a negative growth rate last year. Such a recession has only occurred once before in a Soviet Bloc country -- and the occasion is significant -- Czechoslovakia in 1967.

The effects of the Polish crisis will be seen on several levels. There is the effect on the people of individual East European countries who have their own grievances and aspirations. The crisis has also triggered considerable soul-seaching among other Communist Party leaderships that will be looking for ways of avoiding the same problems at home.

Perhaps most important, the events in Poland will affect the overall relationship between the Soviet Union and its other East European allies. Under heavy pressure in Poland, the Kremlin may be less likely to stifle social and economic experiments elsewhere.

Here is a country-by-country guide of differing, East European reactions:

East Germany, population 17 million: Superficially, East Germany is the most likely candidate for the next explosion. As in Poland, the labor force is young and mobile. The first modern workers' rebellion in Eastern Europe took place there in 1953, also triggered by food shortages. Thanks to West German television, the East Germans have been able to follow the Polish crisis closely night after night. Despite excited discussions, however, few East Germans expect a Polish-style revolt. Living standards are higher than in Poland and there is little tradition of organized dissent. The trade unions are closely supervised by the Communist Party but enjoy more credibility than their Polish counterparts.

Czechoslovakia, 16 million: The leadership has taken a hard-line attitude toward the crisis, hinting at links between strike leaders and "antisocialist circles" in the West. Commentators have drawn a parallel with "antisocialist circles" in the West. Commentators have drawn a parallel with the Prague Spring and called for vigilance and unity among socialist countries in the face of "imperialist threats." But the press has also attempted to provide a safety valve for popular discontent by criticizing shortages and price rises. The dissident movement is fairly large but it has never had much influence among the working class. A possibly more sensitive point is contacts between Polish and Czechoslovak miners. Czechoslovak customs officials are reported to have confiscated copies of the agreements reached between Polish government and strikers.

Hungary, 11 million: Under Janos Kadar, the Hungarians have introduced a market-type economy. Living standards are much higher than in Poland. Dissidents have been treated lightly, although last month seven Hungarian intellectuals were prevented from flying to Poland to express support for the strikers. The Polish crisis has made the "Hungarian model" more respectable in Soviet eyes since Kadar has delivered the valuable political gift of stability. Hungarian coverage of the strikes has been fuller than anywhere else in the Soviet Bloc, but details were still few.

Romania, 22 million: Living standards even lower than in Poland are the rule and, in view of the oil crisis, there is little prospect of improvement soon. The popularity of President Nicolae Ceaucescu, despite his independent foreign policy, is low. There have been reports of scattered strikes, including one by 3,000 workers at Tirgoviste, northwest of Bucharest. In 1977, 35,000 Romanian miners went on strike in the Jiu Valley. This time Ceaucescu has attempted to defuse discontent by promising to cut defense spending by 16 percent and use the money to improve living standards. These promises are unlikely to convice a highly skeptical population but there seems to be little chance of a Gdansk-style general strike. In the past, Romanians have accepted repression much more readily than the Poles.

Bulgaria, 9 million: The Sofia governlment is least of the Kremlin's worries. Despite some grumbling at shortages, most Bulgarians, seem happy with their relationship to Moscow. Thanks partly to Soviet aid, living conditions have improved steadily and there is little of the heavy-handed atmosphere of repression that characterizes some other Soviet Bloc states.

Yugoslavia, 22 million: From its privileged position outside the bloc, Yugoslavia has devoted extensive press coverage to developments in Poland. After a patchy start, when journalists appeared unsure how to react, reporting has been fair and balanced. Yugoslav leaders appear pleased and relieved by the way the crisis has evolved. Privately, they say it confirms the correctness of their own decision to abandon a dictatorial form of communism in favor of decentralized workers' self-management. They also say that with so many bloc problems, the Kremlin is less likely to interfere here in the sensitive post-tito era. As one Yugoslav official remarked: "This has shown just how powerless the Soviet Union is when government and people act together."

Albania, 2.5 million. The establishment of independent unions in Poland has come as a grave disappointment to Albania's Stalinist leadership. At first, the strikes were welcomed by Albanian propagandists -- including a former Polish leader, Kazimierz Mijal, who defected to Tirana disguised as an Albanian trade delegate in 1966 -- as a new "proletarian revolution." But this line has now changed and the strikers are being described as "the tools of the Western bourgeoisie and the Roman Catholic Church."