Four secret policemen went on trial today amid tight security for the murder of pro-Solidarity priest the Rev. Jerzy Popieluszko, and a packed courtroom heard one defendant say that he was told the killing had high-level support and that he had expected to be rewarded for it.

However, former lieutenant Leszek Pecala, the first to take the stand, said he never learned the names of any reported backers. He said he had not intended to murder Popieluszko, just to frighten him.

The trial is widely viewed as having important repercussions for Gen. Wojciech Jaruzelski, the Polish leader, who has called the death of the outspoken, anti-communist cleric a political provocation. Jaruzelski's aides have suggested that hard-line elements in the security forces or in the communist party masterminded the killing to upset the general's policy of accommodation with Poland's dominant Roman Catholic Church, stir unrest and trigger another crackdown.

The central point of attention in the case for many Poles will be what the judicial proceedings reveal about whose orders the policemen acted on, whether political plotters were involved and, if so, how powerful they are.

Although the accused have cooperated in supplying details of the crime, they have been unable or unwilling to implicate any high-ranking co-conspirators. Jaruzelski said at a press conference of foreign reporters last month that the threat of a death sentence might induce the four defendants during the trial to name instigators of the killing.

The murder indictments were read today in the Torun provincial court against Pekala, 32, his partner, former lieutenant Waldemar Chmielewski, 29, and their immediate superior, former captain Grzegorz Piotrowski, 33. The three former officers -- they already have been demoted to privates and expelled from the communist party -- have confessed to kidnaping and killing Popieluszko, but the public prosecutor said in reading the indictment at the start of the trial that the three men did not believe they were acting against state interests but rather were advancing them by getting rid of the controversial priest.

Also charged with aiding and abetting the murder is former colonel Adam Pietruszka, 47, who supervised the three accused officers as deputy director of the Interior Ministry department responsible for surveillance of church activities. The indictment against Pietruska said that he used his rank to persuade the officers to attack the priest and later obstructed the investigation to find them. He has pleaded innocent.

A fifth Interior Ministry official, Gen. Zenon Platek, has been suspended from duty for failure to supervise members of his department. Another officer, a lieutenant colonel in the Warsaw militia identified in newspaper reports only as Leszek W., was detained briefly in November but released for lack of sufficient evidence.

Popieluszko, whose eloquent sermons in defense of the banned Solidarity movement drew large crowds to his Warsaw church, was kidnaped near this city in north-central Poland on the night of Oct. 19. Police divers pulled his badly bruised and trussed up body from a reservoir on the Vistula River in Wloclawek, 45 miles southeast of Torun, 11 days later. An autopsy concluded that the 37-year-old cleric died of suffocation.

His funeral in Warsaw attracted 250,000 people, many of them holding Solidarity banners and hailing the slain priest as a martyr and national hero.

Security surrounding the trial was exceptionally tight. Police used metal barriers to seal off a wide area around the three-story, red-and-yellow brick court building located in a narrow back street of the city's Gothic-style old town. Hundreds of curious onlookers were kept back as an Army helicopter circled low overhead at the trial's start.

Government officials have expressed concern for the safety of the defendants, taking extraordinary precautions to protect them since their arrest. Only those with official passes were allowed in the courthouse, passing through metal detectors and filing past black-bereted, antiterrorist police carrying revolvers and long knives.

About a third of the 100 seats in the courtroom have been reserved for the press. But only six have been allotted to western news organizations, and The Washington Post was not included.

The defendants, dressed in civilian clothes, sat in two rows of raised benches along a wall at the front of the newly-painted courtroom, each man flanked by uniformed guards.

Prosecuting attorney Adam Pietrasinski said that 22 witnesses were scheduled to be heard and that evidence from 62 more would be read in court in coming days. In the indictment against the four, he called the crime a "premeditated, well-prepared willful murder."

The document said Pekala and Chmielewski, the two lieutenants, had confessed to police that Piotrowski told them the order to kill Popieluszko "came from the highest level" of the government. The captain was reported also to have told the men that the operation was "highly secret" and assured them their careers would benefit after the murder.

Piotrowski is quoted in the indictment as denying the allegations of his subordinates, saying the three of them killed Popieluszko because he was plotting antistate activities and the government had been ineffective in stopping the militant cleric.

Questioned by the prosecutor following the reading of the indictment, Pekala said that Piotrowski had called him to his office with Chmielewski in early October and asked them to take part in "a dangerous mission connected with Popieluszko" that could result in the death of the priest, whose health was fragile. The aim, Pekala recalled, was to frighten the cleric into ceasing his opposition sermons and disclosing the hiding places of underground Solidarity activists.

"Piotrowski told me the abduction plan was approved by his superiors," Pekala said. But when asked by the prosecutor who the former captain had named, Pekala replied, "He didn't give any concrete names."

Pekala said several plots were considered, and a first attempt was made Oct. 13 when Popieluszko's car was stoned on the road from Gdansk to Warsaw in an effort to make it crash, but the attempt failed. The three officers have been charged with the earlier attempt as well as with the murder six days later.

The trial will continue tomorrow.