Delegates to the congress of Poland's independent labor union Solidarity rebuked their leader, Lech Walesa, today and censured the union's presidium for its compromise with the government on the issue of worker self-management.

Several of the delegates bitterly attacked Walesa, Solidarity's chief founder, for what they called an authoritarian style of leadership. The congress voted 348 to 189 to censure the 10-man presidium for "the improper" way in which it had agreed to the compromise with the government.

The criticism of Walesa was tempered, however, by a celebration of his 38th birthday, amid clear indications that he is likely to be reelected as Solidarity's president at the end of the congress, despite the reservations of many delegates about his moderate policies.

Delegates, by an overwhelming majority, also passed a resolution approving the activities of Solidarity's national leadership in the year since the union's formation.

In a brief speech, Walesa appealed for tolerance toward the union's outgoing leadership, many of whose members are standing again for top office.

"Nobody should be punished for a lack of democracy. We have to treat the past year as undemocratic since we had no instructions from our members and no program," he said.

The union leader was then showered with birthday greetings as the delegates stood from their chairs to sing "Sto lat, sto lat" (May he live a 100 years) -- a traditional Polish song that reflected Walesa's popularity among the rank and file.

Today's attacks on Walesa were led by one of Solidarity's main inspirers, Kazimierz Switon, who served several jail terms in the late 1970s for propounding the cause of free trade unions. It is widely expected that he may decide to challenge Walesa for the leadership.

Switon accused union leaders -- including Walesa -- of losing touch with ordinary workers.

He added: "The union is being destroyed from within. Unless we get rid of such people as our leaders, we won't achieve anything."

Switon's criticism was supported by Zbigniew Kokot, a delegate from the southern town of Czestechowa, who said that union leaders were fighting for their positions. "What is happening here usually happens in the Communist Party and government, but should not be tolerated in the union," he said.

Several of the attacks were sparked by the new self-management law passed by parliament -- a controversial compromise under which the right to nominate directors was divided between the workers' councils of factories and the government. The idea was approved by four out of 10 presidium members acting on behalf of the entire union.

The resolution stated that the presidium decision had been improper and that such an event should not take place in the future. It rejected Walesa's argument that the leadership was justified in acting as it did as the law was about to be passed by parliament and there was no time to consult the Solidarity congress.

Such a view, the resolution said, was "understandable." But the union's unelected advisers and experts had exercised an improper influence over the decision. "The new union authorities will be obliged to specify the function and competence of the advisers," it added.

The delegates have yet to take a stand on the new law itself. Some union branches are calling for the congress to press ahead with plans for a nationwide referendum on whether to boycott the law, but the issue is still unresolved. CAPTION:

Picture, Solidarity leader Walsea celebrated his 38th birthday at the union's congress.