With factory sirens sounding from the East German border in the west to the Soviet border in the east, Poland's independent trade unions today brought out thousands upon thousands of workers for a one-hour strike to protest government policies.

It was the first time that workers in a Soviet Bloc country had struck in response to an appeal by an independent labor organization to assert their interests.

The decision to stage the protest just one day before an important meeting of the Polish Communist Party's Central Committee has alarmed the country's leadership. The strike was called to draw attention to alleged government delays in implementing agreements reached with striking workers a month ago.

Leaders of the independent Solidarity Union claimed that the strike had been a complete success, but they were unable to estimate the total number of workers involved.

Solidarity Union restricted the strike mainly to those plants that were at the center of last summer's labor unrest and are now the strong-holds of the new unions. In order to avoid disruption of production, many workers participated only symbolically by wearing red and white armbands and hanging the Polish national flag from factory buildings.

Government ministers insisted that they are doing their utmost to fulfill agreements signed with striking workers along the Battle Coast and in one industrial region of Silesia.

The government also launched an intensive propaganda campaign to convince the public that fresh strikes can only further damage Poland's already battered economy and make implementation of the agreements even more difficult. But public opinion still appears firmly on the side of the strikes.

Support for the strike was most complete in the Baltic city of Gdansk, scene of lengthy negotiations last August about the establishment of independent unions. Today, virtually all economic institutions, from the giant Lenin Shipyard to small shops and restaurants, closed down at midday.

Traffic was halted briefly outside the Morski Hotel, the headquarters of the Solidarity Union, when a public meeting of about 3,000 persons spilled over into the road.

Jacek Kuron, a spokesman for the dissident Workers Defense Committee, described the strike as very strong along the coast, at Lublin in eastern Poland, and at Krakow and Katowice in the south.

In Warsaw, workers at half a dozen large factories joined the strike, and most public transport was halted. In smaller towns where the new unions are less well organized or have encountered greater official opposition, support was more sporadic.

Even so, the strike was an impressive demonstration of Solidarity's hold over Polish workers after less than a month in existence. It is the political implications of this show of strength, rather than the economic losses, that most embarrasses the communist leadership.

Allegations by some Solidarity officials that at one point the government had threatened to cancel the Gdansk agreement if the strike went ahead could not be confirmed. The threat was said to have been made by Deputy Prime Minister Mieczyslaw Jagielski during talks on Wednesday evening, but it is more likely that he was just issuing a general warning of the possible negative consequences the strike might have.

The communist authorities have not hidden their concern that their room for maneuver could be limited still further if strikes are used as a means of putting permanent pressure on the government. Hard-liners within the 143-man Central Committee will not doubt point to the strike as evidence of the folly of giving in to workers' demands.

A recurring theme of editorials in the officially controlled press is that Poland needs a peaceful atmosphere in order to be able to solve its economic problems and work toward the introduction of greater democracy. The Communist Party newspaper Trybuna Ludu commented today that these difficulties could not be solved by way of strikes.

A commentary in the daily Zycie Warsawy said no government could work normally under pressure without being given time to settle problems accumulated from past years. It added: "What is worse, the strike will help to unify the opponents of the government and provide them with ready ammunition."

Such agreements, however, appear to be making little headway with the population. Most people questioned at random on the streets of Warsaw expressed full support for the strikers and blamed the government for the lack of goods in the shops.

A rare note of discord was struck by an elderly man at a bus stop who complained that he had been waiting over half an hour for a bus. He grumbled. c"Okay, let them stage their strike, but I don't see why they should inconvenience the public. Why make it difficult for ordinary people to go about their daily business."

At the Warsaw steelworks, members of the founding committee of the independent union marched around the plant chanting "solidarity" and "no more lies." They bore placards printed in the plant printing shop demanding wage increases for the lower paid and freedom of speech.

Polish flags hung from many institutions in the city including some post offices and the university where a new academic year is about to begin. Students have also demanded the right to form independent unions.

At the Ursus Tractor Plant south of Warsaw the scene of large-scale workers' disturbances in 1876, some 1,500 workers ceased work altogether while others just showed their support for the strike by wearing armbands. Workers complained about the lack of objective reporting in the press and initial threats of harassment against the new unions.

Polish television reported the strike as the main item on its evening news broadcast, showing film of idle ships in ports and workers manning picket lines outside factories. It described the strike as "a demonstration of the workers' strength of which we are all aware," but added that, it was not necessary to prove it in this way.

Despite its clear pro-government bias, the coverage devoted to the strike by radio and television contrasted sharply with the lack of reporting of labor unrest just two months ago. When asked what memory of the crisis will remain most vivid in their minds, many Poles cite the moment toward the end of August when a television broadcast first used the previously taboo word "strike."