Government authorities claimed broad public support in Poland's legislative elections today, but opposition leaders who had called for a boycott said millions of people stayed home despite official pressures and threats of reprisal.

Several Warsaw leaders of the banned trade union Solidarity were called in for questioning, and dozens of detentions were reported in other cities as the government urged about 25 million eligible voters to cast ballots in elections for the 460-member legislature, or Sejm.

Authorities reported antigovernment street demonstrations by several hundred persons in Gdansk and the Krakow industrial suburb of Nowa Huta following Sunday masses. Several police were reported injured in Nowa Huta by youths who tore down election-day flags, set off firecrackers and threw stones.

Government spokesman Jerzy Urban said this evening that about three-quarters of Poland's eligible voters had cast ballots by 7 p.m., three hours before polls closed, and that the overall turnout would be higher than in the June 1984 local elections, when 74.95 percent of Poles were officially reported to have voted.

"A general support was expressed for the political line of the state," Urban said. He added that the elections "were a confirmation of our intentions. Society reacted wisely, independent of its doubts and criticisms, some of which are shared by the government."

Solidarity leader Lech Walesa disputed the government's account, saying the turnout at midday was far below the official figures. He predicted that the turnout would be below 50 percent in his hometown of Gdansk.

By both government and opposition measures, voter participation was well short of the 98.9 percent turnout recorded in Poland's last legislative elections in 1980. Western diplomats here said the discrepancy amounted to an official acknowledgment of the continuing public resistance to the government of Gen. Wojciech Jaruzelski nearly four years after it repressed the Solidarity movement.

Jaruzelski portrayed the election as a referendum on his policies of "normalization," and today's vote was preceded by a two-month campaign of public meetings, carefully orchestrated "consultations" of citizens and intensive propaganda.

Governmental and communist party officials have suggested that the campaign was meant to set the stage for a postelection shake-up in some government positions and a more aggressive implementation of policies to reform the economy and neutralize political opposition. Jaruzelski recently said that the new Sejm could consider an amnesty for political prisoners if turnout in the elections were high.

Solidarity responded with leaflets and clandestine radio and television broadcasts branding the elections a sham, offering voters no real choices. The union also claimed to have mounted its own independent system of exit-polling to determine turnout.

Both sides were disappointed by the stance of the powerful Roman Catholic Church, which refused to take a position on whether citizens should vote. State television today showed footage of some priests casting ballots, but Urban said tonight that the majority of priests had not voted. Poland's primate, Cardinal Josef Glemp, passed the day in Rome, and no member of the church hierarchy of cardinals and bishops publicly reported participating.

Opposition activists and some voters said today that official tactics of intimidation and threats of reprisal had forced some citizens to turn out. The measures included visits to homes of previous nonvoters by local officials, and warnings to those seeking jobs and apartments that they would not qualify if they did not vote.

Two Solidarity advisers in Warsaw, Jacek Kuron and Zbigniew Romaszewski, were summoned to the Interior Ministry this morning to be interrogated for the second straight day. Both signed a public appeal for an election boycott last month, and Romaszewski last week reported beatings of several political prisoners.

Urban said that the two men were called in for questioning on their reports of recent abuses by police and prison guards and that the summons were unrelated to elections. He confirmed that a number of persons around the country had been detained in recent days but said no figures would be released until Tuesday.

The long lines, blaring sound trucks and pamphlet-laden poll workers that are familiar sights of western elections were absent from Warsaw, where streets decorated with flags and bunting retained the still of a cold Sunday.

Voters who arrived at polling stations were greeted by a committee of officials who checked their names off neighborhood lists before handing them separate ballots for the 50-member "national list" of unopposed Sejm candidates and district slates in which two candidates competed for each of several seats.

Despite the choices, a majority of voters did not bother to enter voting booths or to mark their ballots at all, election officials in several locations said. Under election rules, blank ballots are counted as votes for officially favored candidates in each race.