Although one major Warsaw Pact military exercise in and around Poland has ended, senior U.S. officials said yesterday that Soviet-bloc forces remain ready to intervene in Poland if necessary and that there were signs of increasing Soviet political pressure on Polish authorities.

In the aftermath of a generally moderate speech in Czechoslovakia Tuesday by Soviet President Leonid Brezhnev and the announced termination by Moscow of the Soyuz-81 military exercise, both U.S. and some European observers here felt that the focus of the tense standoff between moderate and hardline forces in Poland would now shift more noticeably to the question of who will control the Communist Party in Warsaw.

In this view, while the independent Polish labor movement, Solidarity, poses the most visible and immediate threat to Communist Party authority, what concerns Moscow most in the long run is that the party leadership itself may become too liberal not only for the Soviets but for the rest of the Soviet-bloc governments in Eastern Europe.

Senior U.S. officials view the overall situation in and around Poland as now "on hold" and believe the next important clue to the future may come in Friday's meeting of the Polish parliament rather than in a military headquarters.

Officials here believe that the line dividing the politburo in Warsaw is more clear than ever. Stefan Olszowski, a politburo hardliner in charge of ideology and propaganda who traveled to Prague this week to meet with Brezhnev, is emerging as the most likely alternative for Moscow to the more moderate current leadership of party chief Stanislaw Kania and the prime minister, Gen. Wojiech Jaruzelski.

Jaruzelski has not been seen publicly for several days, since it was announced on April 4 that he was "temporarily indisposed." While this has prompted some curiosity here, officials say they have no reason to believe it is anything more than a passing illness.

At the State Department yesterday, spokesman William J. Dyess also called attention publicly to the signs of increased political pressure on Polish authorities to crack down on elements challenging the orthodox style of party leadership favored by Moscow.

In his speech to the Czech Communist Party Congress in Prague, Brezhnev, without referring specifically to the Polish party led by Kania, declared that "the Polish communists, with the support of all genuine patriots of Poland, will be able, one should suppose, to give a fitting rebuff . . . to the enemies of the socialist system." Yesterday, Dyess said Brezhnev's speech "gives us no clear idea of Soviet intentions. While it seems to be designed to give some reassurance on the issue of Soviet military intervention, the speech did not rule out any options."

Furthermore, Dyess said, "Brezhnev's remarks on the political situation appeared designed to place additional pressure on the Polish authorities." The Reagan administration has stressed that it is opposed to both outside military intervention and an internal crackdown.

Through Dyess took note of reports from the East that the Soyuz exercises had ended, he said in effect that they have ended in name only, because the military situation in and around Poland "remains essentially unchanged." He indicated there are other military maneuvers still going on and the United States "continues to observe an unusual level of military activity" in the region.

Privately, officials confirmed that the Soyuz exercise had, in fact, ended. They added, however, that there was no indication thus far that Warsaw Pact troops involved in even that limited exercise were going back home, as government reports from Moscow and Prague had claimed. Sources said that there had been neither an increase or decrease in the intensity of military readiness, that nothing connected with the exercise had been dismantled, and that the Soviets were still maintaining a communications system that allowed them to bypass the Polish government if necessary.

Though a relatively small number of troops, perhaps fewer than 25,000, reportedly took part in the Soyuz exercise, the Soviets still have between 12 and 20 divisions in areas around Poland in addition to two divisions long based inside Poland.