The leader of Poland's independent Solidarity trade union, Lech Walesa, called today for immediate negotiations with the communist authorities as Solidarity's first national congress came to an end.

Walesa's call came as Solidarity's newly elected leaders met in Gdansk to choose a 12-man inner cabinet to make day-to-day decisions for the union. The result of this presidium election was seen as a personal boost for Walesa, who had argued in favor of a strong central leadership.

Walesa had earlier found himself in danger of being outvoted on the union's National Consultative Committee, many of whose 107 members favor more radical policies. Several of his closest advisers failed to win seats on the committee.

In addition to the cabinet, the Consultative Committee also elected a liaison group composed of six representatives of the most powerful union branches. They will travel around the country to keep the rank-and-file in touch with the leaders' decisions.

As most of the 892 congress delegates left Gdansk for home, Communist Party leaders began assessing the results of the two-stage, 18-day meeting. The first reaction appeared to be that, despite the intransigence of some delegates and the political tone of many of the final resolutions, it could have been much worse.

In Moscow, the Soviet Tass news agency condemned Solidarity's newly adopted platform as a counterrevolutionary document, Reuter reported. Tass charged that Solidarity was trying to place itself "above the party, the government, and above the (parliament)."

In an interview, Poland's First Deputy Premier Janusz Obodowski agreed that the second round was more acceptable to the government than the first, which ended with a demand for free elections and a message of support for other Eastern European free trade unionists.

Asked whether this meant there could be early talks between Solidarity's leaders and the authorities, he replied: "What other choice do both sides have except negotiations?"

Government-union negotiations were virtually suspended during the congress as a result of an earlier collapse of talks on Solidarity's demands for greater access to the news media. A resolution adopted by the congress calls for a nationwide warning strike within two weeks unless agreement is reached over price rises and economic reform.

Only after a meeting of the Communist Party's policy-making Central Committee, scheduled for next Wednesday and Thursday, will the regime's response to the congress become clear. The session could also determine the political future of the party leader, Stanislaw Kania, whose authority has been undermined by the continuing labor unrest.

There are threats of at least half a dozen regional strikes over issues ranging from harassment of Solidarity activists to poor food supplies. The Solidarity congress has appealed for a suspension of local protests pending talks with the government.

In an interview for Polish radio, Walesa said that talks were needed before winter, adding : "Without mutual trust, it will be impossible for us to get out of this mess. I think the time has come for us all to sit down at the table and start working for the good of all the people. . . . We remember that we are first of all Poles. We must rescue the economy and rescue the country."