Poland's Communist Party today began legan proceedings against a former prime minister for crimes possibly committed while he was in office.

It also took steps that could lead to punishment or humiliation for a dozen other former party and government officials, including Edward Gierek, the former party leader.

The party's Central Committee, in its final meeting before a crucial party congress opens Tuesday, also heard a report from a special committee probing into official corruption that 26,000 people had been investigated and that the charges had been found justified in 12,000 cases.

Despite the impressive figures, however, few people have actually been indicted or convicted on the corruption charges, and it is unclear whether today's report and the actions taken will satisfy rank-and-file party members who have urged that the investigations continue after next week's party congress.

Politburo member Tadeusz Grabski, who headed the investigating commission and presented the report, told the Central Committee that the party must turn its attention away from the past toward finding ways to overcome the crisis that has split the party and raised tensions between Poland and the Soviet Union.

In a resolution passed at the end of a one-day meeting, the Central Committee raised the possibility that Gierek, Poland's Communist Party leader throughout the 1970s, will be dropped from the party. Gierek's case, along with that of four of his closest aides, is to be considered by the party control commission, the first step toward possible expulsion.

The resolution instructed the prosecutor general to investigate Piotr Jaroszewicz, who was prime minister from 1970 to 1980, to see whether he was guilty of crimes under a section of the criminal code covering misuse of office and neglect of duties.

Political analysts here regarded the resolution as an attempt to settle the highly emotional issue of responsibility for Poland's present political and economic crisis before the start of the congress. Demands to "bring the guilty to account" have been a recurring theme at political meetings throughout Poland over the past 10 months.

Today's Central Committee meeting heard what was described as "a final report" from the investigating commission headed by Grabski.

Grabski, regarded as one of the hard-liners on the Politburo, said that any decision to bring a former prime minister to trial for mistakes committed in officed would be unprecedented in modern Polish history and would have to be considered very carefully.

He also drew a distinction between criminal and political offenses, explaining that only officials who filled state or government posts could be brought to trial. Communist Party leaders responsible for political errors of judgment could only be dishonored, he said.

This would appear to mean that, although Gierek must bear much of the political blame for leading Poland into the crisis, he will not face criminal charges. Grabski, however, announced that legal action was to be taken to recover a villa now occupied by Gierek in Katowice that allegedly was built with state funds.

The attorney general has also been instructed to attempt to recover the costs of a villa owned by the Gierek family in a mountainous district of southern Poland.

Last week parliament's special investigating bureau accused a large group of politicians of "irregularities" in acquiring their weekend houses. In addition to Gierek, the list included two other former Central Committee secretaries, 57 provincial secretaries seven former deputy prime ministers, 18 ministers and 56 deputy ministers.

Referring to those such as Gierek, who had committed "political errors," he said: "They will have to live with the weight of responsibility for their mistakes, and it is in this way that their names will go down in history. They have gone through the process of political degradation like a military commander who is publicly deprived of his rank, medals, fame and distinctions."

According to a report by the parliamentary investigating bureau, however, only 59 persons have been indicted for crimes involving corruption or abuse of office.

The former politicians recommended by the Central Committee for deprivation of medals include many of the most powerful men in Poland during the 1970s. In addition to Gierek and Jaroszewicz, they include: Edward Babiuch, a former prime minister; Jerry Lukaszewicz, former propaganda chief; Zdzislaw Grudzien, a Politburo member; Tadeusz Wrzaszczyk, planning chief, and Tadeusz Pyka, Jan Szydlak and Franciszek Kaim, all deupty prime ministers.

In an attempt to prevent similar "distortions" in the future, the Central Committee resolution proposed stricter controls over the Politburo and party bureaucracy, limits to the powers of the prime minister and his ministers and an annual vote of confidence in the government.

Another official accused of corruption by the independent trade union federation Solidarity has resigned. Andrzj Antosiak, the director of city transportation in Bydgoszcz, announced his resignation following a two-hour transport strike in the city yesterday.

Elsewhere in Poland, however, new signs of labor unrest emerged over poor food supplies. In the railway junction town of Kutno, west of Warsaw, token stoppages were held today and a two-hour warning strike has been called for Monday. A march of "starving children" has been announced for next Wednesday.