Poland's premier, Jozef Pinkowski, was replaced tonight by an Army general in an apparent attempt to shore up the country's weakened political leadership.

The new premier is Gen. Wojciech Jaruzelski, 57, defense minister since 1968 and a longstanding member of the ruling Politburo. His suprise appointment to become Poland's fourth premier in less than a year reflects the government's failure to reach a smooth working relationship with Solidarity, the communist world's first independent trade union federation.

Industrial unrest continued today, as workers at about 400 factories in the southwestern province of Jelenia Gora ignored the pleas of Lech Walesa, Solidarity's leader, and went ahead with a general strike over local grievances.

Despite the change of premiers, there are no indications that Stanislaw Kania, who took over as head of the Polish Communist Party in September, is in immediate danger of losing his position.

Pinkowski's dismissal, which had been widely rumored in Warsaw during the last few days, also reflects his failure to steer the economy out of deep crisis. Last week it was announced that the national income had dropped for the second year running, this time by 4 percent.

The change of premier was announced at the end of a meeting of the Communist Party's Central Committee, where members called for a stronger line against continuing industrial unrest and peasants' demands for an independent union.

Jaruzelski's promotion and the tough rhetoric emerging from the Central Committee plenum appeared at least partly designed to reassure Poland's worried Soviet Bloc neighbors of the Communist Party's ability to control events here. During the past week, official news media in the Soviet Union East Germany and Czechoslovakia have stepped up their criticism of Solidarity and, by implication, the Polish leadership.

Although Jaruzelski is known in the Army as a disciplinarian, he is regarded as a moderate in Polish political terms and is believed to have argued strongly against the use of force to crush workers' unrest last summer. During a previous crisis, he is reported to have advised his Politburo colleagues, "Polish soldiers will not fire on Polish workers."

Nevertheless, the fact that an Army general has been appointed premier -- an almost unique event for a communist country -- could signal a distinct change in the government's handling of the crisis. More than any other Polish politician, Jaruzelski can claim to have the backing of the country's 300,000-strong armed forces.

Jaruzelski, who served during the war in the Soviet Union, takes on the premiership at an extraordinarily complicated time. The Polish economy is in chaos and no end appears to be in sight to the industrial unrest sweeping the country.

During the past month, government policy toward Solidarity has sometimes appeared to shift daily -- and many observers believe the lack of consistency has helped fuel industrial unrest. Occasional displays of toughness have served to antagonize the workers, while later readiness to compromise has been taken as a sign of weakness.

Jaruzelski in Poland's fourth premier is less than a year. This provides an accurate reflection of the political turmoil the country has gone through following a breakdown of trust between communist authorities and the workers.

News of the change in prime minister was broadcast in late-night radio bulletins well after most Poles already had gone to bed. A session of the Polish parliament will be held Wednesday and Jaruzelski is expected to name his new Cabinet then.

Pinkowski, an economist with singular lack of charisma, served as premier for less than six months. He was named on Aug. 25 following the resignation of Edward Babiuch, whose decision to raise meat prices sparked last summer's strikes.

Babiuch replaced the long-serving and highly unpopular Piotr Jaroszewicz in February 1980. Last week, in a move that pleased many Poles, it was announced that Jaroszewicz had been stripped of his membership of the Communist Party for gross policy errors and arrogance.

Today's Central Committee plenum heard strong criticism of Solidarity by several senior party officials. But, despite the uncompromising language, little indication was given of what the party proposes to do if Solidarity fails to fall into line.

Ironically, in view of Jaruzelski's appointment, among the strikes in progress is one by 40,000 students, protesting among other things at the length of compulsory military service. Student representatives were shown on television this evening negotiating on the issue with an Army general, another unprecedented sight for a Warsaw Pact country.

Meanwhile, in a keynote speech to the plenum, a senior party official, Kazimierz Barcikowski, stated flatly that the Politburo found no justification for the establishment of an independent union for peasants.

Coming just the day before the Polish Supreme Court is to consider the application for legal registration by Rural Solidarity, as it is known, this represents the most explicit opposition yet voiced by a party leader to the organization.

Earlier it had appeared that the communist authorities were seeking a way around the deadlock in negotiations with representatives of Poland's 3.5 million farmers. A speech by Kania last week, while critical of Rural Solidarity, left open the possibility of a compromise on the issue of its registration.

Several hundred farmers traveled to Warsaw today from the southeastern city of Rzeszow, where they have been staging a sit-in at local administrative offices to lobby the Supreme Court.

Calling for statutory regulation of the right to strike, Barcikowski condemned what he called "strike terror against factory crews" and increasingly political protests."

His criticisms were echoed by another leading Politburo member, Tadeusz Grabski, who claimed Solidarity was being used by dissidents for antistate purposes. He singled out activists of the dissident Committee for Social Self-Defense, known as KOR, whom he accused of attempting to push the union toward "destructive action, adventurism, and finally counterrevolution."

The touch language at the Central Committee session, which is to continue Tuesday, masks the fact that the authorities find themselves in a very weak position. Significantly, despite the uncompromising language, there was little indication of what the party proposes to do if Solidarity fails to fall into line.

The decision to strike in Jelenia Gora was made after the collapse of talks with government negotiators Sunday night. The principal issue is the workers' demand that a modern sanitorium under construction for employes of the Interior Ministry -- the national police -- should be turned over to the general health service.

Other strikes in progress include one by tens of thousands of students in Lodz. Miners in the southern industrial region of Silesia and newspaper printers have threatened to strike later this week.

In his speech, Grabski described the Jelenia Gora strike as "a blatant provocation."

The speeches at the plenum reflected the recurring dilemma that has confronted the Polish Communist Party since the onset of the crisis six months ago. The Polish leadership has to chose between satisfying the concerns of their Soviet Bloc neighbors and its own entrenched bureaucratic elite or attempting to regain the confidence of the country's alienated work force.

So far, party leaders have attempted to steer a middle course between the conflicting interests of the two groups. Their speeches are designed for both internal and external consumption. Now, with the Soviet Communist Party congress just two weeks away, the Polish leadership apparently feels the need to convince the Kremlin that it remains worthy of its confidence.