Poland's Gen. Wojciech Jaruzelski offered a partial amnesty to political prisoners and suggested strong measures to stabilize the economy as he reported today to the Polish communist party congress with Soviet leader Mikhail Gorbachev present.

In a four-hour speech that reviewed much of Poland's political life, Jaruzelski defended his suppression of the Solidarity independent trade union in 1981, strongly attacked its remaining leaders and ruled out any return to pluralism in the country's trade unions.

However, he promised tolerance for dissenting views and conceded that his government still faces "a heritage of grudges, disillusionment and distrust."

"The tempo and degree of overcoming difficulties are varied," he said. "We are aware of the fact that barriers both in the material sphere and in social consciousness can be overcome only gradually."

Jaruzelski said "it could be possible to offer one more chance" to the more than 300 political prisoners through a partial amnesty, the fourth since 1983. He did not say when the release would take place or how many imprisoned activists might be freed, but he indicated that only "certain categories" of offenders would be included.

The speech included ringing pledges of allegiance to the visiting Gorbachev, whom Jaruzelski called "our good friend" and the originator of "momentous initiatives for the development of socialism." Gorbachev, who is expected to address the congress Monday, quietly observed the day's events from a seat beside Jaruzelski.

The congress is the first since July 1981 for the Polish United Workers Party, as the ruling communist party is formally called, and appears carefully planned by the party leadership as a businesslike showcase of Jaruzelski's "normalization" of the country.

"We have stated that our congress is ordinary, but it is also of a particular nature," said Jaruzelski, who holds the country's top party and state positions. "It closes down an extremely difficult stage in the life of the party and country."

The congress was preceded by a crackdown on opposition activity and interrogations of senior Solidarity officials in an apparent effort to prevent any show of resistance.

Jaruzelski's speech began at a time when millions in this strongly Roman Catholic country normally attend mass, and several thousand Solidarity supporters in the western city of Poznan began a march after a service commemorating the anniversary of riots by workers in 1956. The demonstration was quickly put down by police and western reporters said some protesters were beaten.

Tonight, another big opposition crowd gathered at the St. Stanislaw Kostka Church here for a monthly "Mass for the Fatherland," and some chanted antigovernment slogans as they left. Hundreds of riot police were stationed around the church.

Jaruzelski said "hesitation and disillusionment, distrust and passiveness" were characteristic of many Poles, and added, "There is no way to win everybody." But he said support for the opposition was rapidly declining, and he condemned Solidarity's remaining structures as "instigated and supported by alien forces."

He also condemned "the antisocialist clericalism articulated by some of the priests," which, he said, "casts a shadow upon the relations between the state and the church." He said the government sought improved relations with the Catholic Church hierarchy and the Vatican but he made no reference to church efforts to gain full legal status, regain control over charitable organizations and set up a foundation to support private agriculture.

Jaruzelski's defense of his political stand was accompanied by assertions that Poland's attention should now be focused on solving economic problems. "In the past few years it was political agreement that had been in the foreground. Now, socioeconomic cooperation is of particular importance," he said.

In a long discussion of his four-year-old program of reforms of the economy, Jaruzelski said that "the basic assumptions" of moves to decentralize management and introduce capitalist-style market incentives "are right," but he admitted that "no breakthrough in effectiveness has taken place."

He called for a "second and decisive stage" of reform and proposed that a new task force reorganize the central bureaucracy.

Jaruzelski also hinted that "a regime of austerity and work discipline" might be necessary to achieve a gain in efficiency and restore stability to a domestic marketplace still plagued by shortages and inflation.

In reviewing foreign policy, the Polish leader bitterly accused the United States and other western countries of an "illegal, brutal attempt at interference in the internal affairs of our country" that "has become one of the present-day manifestations of the Cold War."

Jaruzelski charged that "Washington has become a prime mover and the main executor of decisions and actions to Poland's detriment," and called the "balance sheet" of U.S.-Polish ties "still very unfavorable." But he observed that "some reasonable circles" in the United States understand "that the impasse, now in its fifth year, cannot bring about any benefits" to either side.