They called each other "comrade" and stood to attention as the communist anthem, "The Internationale," echoed through the congress hall. Then, one after another, they blamed the Communist Party Leadership for Poland's troubles -- and demanded the democratization of the party.

Before the unprecedented national conference of rank-and-file party activists ended tonight, some 750 delegates from all over Poland adopted a resolution calling for the next Central Committee meeting to expel from the Politburo "those members who have lost the trust of the rank and file." They suggested that regional party chiefs who had resigned their positions be replaced on the Central Committee by workers.

A delegate from Bydgoszcz summed up the tone of the meeting when he said: "We party members have lost trust in the party apparatus at every level. We have to break radically with 36-year-old habits of inner party life. We are convinced that the biggest break on reforms is the party apparatus itself."

[The government, meanwhile, withdrew yesterday's announcement that it was extending food rationing to cover a range of basic items including butter, flour, and rice. The decision followed complaints by the Solidarity trade union federation that it had not been consulted on the issue.]

The conference of representatives of the self-styled "horizontal movement" reflected growing initiatives by rank-and-file Communists for reform. In contrast to numerous such meetings throughout Poland, this was the first effort to gather reformist-minded party activists on a nationwide basis. As such it poses a serious challenge to the party leadership.

Meeting today in this northern town, best known as the birthplace of the medieval astronomer Copernicus, delegates angrily rejected allegations of factionalism -- the creation of a party within a party, which is a cardinal sin in Marxist-Leninist dogma. They insisted that their goal was to force the existing party to live up to its own ideals.

The extent of their support could not be determined. But the movement's cumbersome name reflects the fact that many ordinary party members no longer trust the traditional "vertical" structures in which they were expected to passively carry out instructions conveyed to them from above. Instead, local party cells in factories, offices and colleges have formed new "horizontal" groups -- bypassing the party leadership -- to canvass the need for change.

The meeting took place against a background of considerable bitterness among many rank-and-file Communists at the inconclusive results of the last Central Committee meeting in Warsaw. Despite demands by some factory party cells for a final showdown with conservatives in the leadership, the ruling Politburo remained intact.

The rank and file is now concentrating attention on the next Central Committee meeting which is due to be held by the end of this month. At today's meeting, delegates repeatedly called for the dismissal of "hard-line elements" whom they accused of "blocking reforms" and for a live broadcast of the proceedings of the meeting.

The credo of the horizontal movement is simple. In the words of Marijan Kallas, a lecturer at Torum University, "We want to bring about the democratization of the party followed by the democratization of the state. What is more, we believe that this process can only be accomplished by the party base."

The idea was born back in October last year, shortly after the explosion of workers' unrest, when the Communist Party was in a "state of coma."

The attitude of the party hierarchy toward the horizontal movement gradually has been changing. At first, with the exception of a few reformist strongholds such as Gdansk, it was one of undisguised hostility. Even now, in some parts of Poland, any mention of horizontal groups is rigorously censored from the press.

After first criticizing the movement, some party leaders have now come to terms with it. In Torum itself, a town with a reputation for political conservatism, there is now smooth cooperation between the "precongress consultive committee," as the horizontal groups call themselves, and the local party authorities.

The two bodies still argue over a number of points, however. The most controversial is the celebrated Iwanow affair -- named after the party secretary of a local factory who was stripped of his party membership because of his outspoken views.

Zbigniew Iwanow, however, won a vote of confidence from his own party organization, which insisted that he remain at his post. This gives him the unique claim to being possibly the only Communist Party secretary in the world who is not formally a party member. He is, however, a leading figure in the horizontal movement.

In his speech, Iwanow suggested that party secretaries from major factories picket the forthcoming Central Committee plenum in Warsaw in order to pressure the meeting to adopt reforms. "They at least could be accused of being antisocialist elements."

Many delegates to the meeting complained about the delay in holding a planned Communist Party congress which is likely to lead to a major shakeup in the Central Committee and the formulation of a new party program. The congress was originally due to have been held in March or April but has now been postponed until July.

The resolution also called on the party leadership to send a letter to Poland's Warsaw Pact neighbors describing "the real state of affairs" in the party and the country. Many speakers said that a false image of Poland was being presented abroad, depicting a country in the grip of "antisocialist forces."