Poland's state-controlled press, normally averse to reporting events embarrassing to the Communist government, is providing extensive coverage of the murder trial in Torun against four secret police officers accused of killing a Roman Catholic priest who was an outspoken supporter of the underground union Solidarity.

Not since the mid-1950s have Polish security agents faced public trial for brutal actions. One difference between then and now, say Poles who witnessed the earlier hearings, is the wide publicity given the Torun proceedings. Reports on the trial have provided rare insights into the attitudes and inner workings of at least one part of the country's shadowy security apparatus.

The Polish press agency publishes long accounts daily of courtroom testimony. Television each evening shows a brief clip of the scene in the courtroom. And radio airs about a half-hour of recorded testimony every night.

Polish newspaper reports tend to be straight narrative accounts of what was said, with little attempt made to highlight the most significant aspects. But by Communist standards, the coverage is unusually detailed.

Many Poles say the government here decided to hold an open trial to recover some credibility and assuage the widespread anger and bitterness felt over the sensational killing of the widely beloved Rev. Jerzy Popieluszko.

On another level, publicity about the case is also understood as a way for Gen. Wojciech Jaruzelski, the Polish leader, to instruct his police to keep within the law in the future, or at least to stay under his firm command and that of a close ally, Gen. Czeslaw Kiszczak, the interior minister.

Grzegorz Piotrowski, the secret police captain who led the abduction and murder of Popieluszko, testified this week that he was driven to lawless action out of frustration with the indecisiveness of his superiors in curbing the cleric's opposition activities.

Piotrowski's impatience with government inaction was thoroughly reported in the Polish press. It drew this commentary -- no doubt reflecting Jaruzelski's thinking -- in the main Communist daily, Trybuna Ludu: "The logical construction presented by the defendant lacks this basic reflection: For every functionary of people's Poland, including the employes of the Interior Ministry, the question of fighting evil through lawless action cannot exist. There is only one thing -- the law. One carries out his duty to protect the interests of the people's state by observing the legal regulations, by applying these regulations to everybody."

In much of the rest of the Soviet Bloc, however, coverage of the Popieluszko affair has ranged from condensed in Hungary to minimal in the Soviet Union. Representatives of Eastern European news agencies have passes to attend the trial in Torun, 120 miles northwest of Warsaw, but most have not gone.

Because the courtroom can seat only 100 people, Polish authorities say they have been forced to limit attendance. Among the Polish reporters admitted are several who write for Roman Catholic publications. But Wanda Falkowska, the reporter of Poland's leading Catholic weekly, Tygodnik Powszechny, had her trial card withdrawn at the last minute.

The government said the reason was lack of space, but she and the paper's editors said the real cause was displeasure in police circles with her coverage of past trials.

Apparently to balance the discomfort felt by police at seeing their ministry critically spotlighted, Communist papers have lately run more stories embarrassing for the Roman Catholic episcopate. They have reported, for example, trials of two insane priests for violent crimes, and a parishioner's protest against the removal of a priest in a southern Polish village.

The rise in this sort of unflattering publicity drew an unusually sharp rebuke last Sunday from Cardinal Jozef Glemp, the Polish primate, who said such propaganda against the church "will not lead to anything positive."

Ten seats in the courtroom -- three more than at the start of the trial -- have been set aside for reporters working for western publications.

The criteria for selection among the 60 or so accredited western correspondents in Warsaw were vague. Fluency in the Polish language was one factor, but not the only one.

Asked last Saturday to explain the basis of selection, Justice Ministry spokesman Andrzej Cubala said: "It is difficult to give the criteria. There were certain general principles, but no details of why."

Having decided in principle to open the trial to the western press, Polish officials have devised a system of access so limited and rigid that many correspondents and diplomats here say they fear it is likely to produce inaccurate or distorted coverage of the proceedings.

Officials at Interpress, the Polish agency that services foreign journalists, said they had assumed that the reporters admitted to the trial would share notes with their coleagues kept outside.

But in the absence of a formal "pool" arrangement, which would have obligated those inside to give full accounts to competitors outside, some of the reporters with passes have been reluctant to relay information to others.

"I don't mean to sound like a professional mercenary, but my first obligation is to The New York Times," said that paper's Warsaw bureau chief, Michael Kaufman, who is among those given a pass. Kaufman later agreed to give limited accounts of the courtroom action to The Associated Press, which is among those left out.

Reporters on the outside have been scrambling to piece together a picture of the trial from sometimes incomplete or conflicting reports provided by Polish as well as western observers inside.

"We have to work twice as hard to guard against inaccuracies and distortions under these circumstances," said Robert Gillette, Eastern Europe correspondent of the Los Angeles Times.

To complicate matters, not all the western reporters authorized to attend have been taking advantage of the opportunity, but authorities refuse to give others the unused passes.

Reporters for western publications granted trial passes are: Gert Baumgarten, who writes for newspapers in Stuttgart and Hannover, West Germany; Christopher Bobinski of Britain's Financial Times; Karol Cwinarowicz of the British news agency Reuter; Kaufman; Bogdan Turek of United Press International; Piotr Wilczynski of the West German news agency DPA, and Witold Ziolkowski of the Italian news agency ANSA. In addition, access was granted this week to two Poles working for Time and Newsweek magazines and to a Norwegian correspondent.

Authorities have rejected pleas by other western reporters to establish a formal pool arrangement or a system of rotating passes.

Maj. Wieslaw Gornicki, an aide to Jaruzelski, told Gillette that while the government is interested in seeing the trial receive wide coverage in the West, it is reluctant to mandate a pool arrangement, fearing that would be interpreted as dictating how western reporters operate in Poland.

Western television networks also have had a frustrating time, being excluded from the courtroom except for 10 minutes the first day of the trial. Network staffers standing outside the old brick courthouse behind police barricades have complained of harassment by militiamen in the form of detentions and time-consuming document checks. Three American networks -- CBS, NBC and ABC -- protested the police actions in a joint letter to the Foreign Ministry. "I can testify to a general nastiness in police treatment," said Alma Kadragic, ABC's Warsaw producer. "We're not breaking any laws we know about. This is just unnecessary harassment."

Polish authorities tend to be sensitive to western news reports because many dispatches filed from here are broadcast back to Poland on the Voice of America and other western-financed stations with programs in Polish.

Reporters at the trial say being inside has its aggravations, too. The daily hearings last six or seven hours. Seats are on hard wooden benches. There are few recesses, no places to buy lunch in the courthouse and no opportunity, because of tight security, to leave the building and reenter.

Security concerns also dictate that bulletproof windows in the courtroom stay shut, giving no relief from the heat and stuffiness in the crowded chamber, made worse by the bright lights of Polish television cameras.