A security agent charged with murdering the Rev. Jerzy Popieluszko today angrily alleged that Roman Catholic priests were getting away with illegal actions in Poland and he depicted the country's police leadership as indecisive and too tolerant toward the church.

The bitter attack by Grzegorz Piotrowski, a former Interior Ministry captain accused of leading the killing, came in his second day on the stand as he sought to bolster his defense that the ineffectiveness or absence of legal measures to restrain the outspoken cleric drove him to take lawless action against the priest.

Piotrowski repeated charges he made yesterday that portrayed Popieluszko not only as an underground activist but also corrupt.

But asked at the end of the day how he now feels about the death, Piotrowski appeared choked with emotion. He said he feels guilty for the suffering he has caused many, citing the priest's family and two subordinate officers he recruited for the operation, and said he, too, had died the night Popieluszko was killed.

Chief Judge Artur Kujawa, meanwhile, drew protests from attorneys for Popieluszko's family when he seemed to join the defendant in criticizing the slain priest. Kujawa read a string of abusive anticommunist epithets said to have been authored by Popieluszko in announcements at his church in Warsaw. The documents had been included as evidence in an earlier government case against Popieluszko that charged him with abusing his religious position.

Lawyers for Popieluszko's family strongly objected to the material being introduced at the trial, arguing that it was never proven that Popieluszko had written the texts, that they bore no relation to the trial and that the charges against the priest had been dropped last summer under an amnesty.

Kujawa said his purpose was to challenge Piotrowski to admit his hatred for Popieluszko, after claiming yesterday that his attitude toward the priest had been one of professional coolness. Citing pretrial testimony by Piotrowski, the judge quoted him describing the mood in the Interior Ministry when Popieluszko was released after a police search of his apartment in December 1983 allegedly found underground publications and explosives.

"I could name you grown men who cried like children when Popieluszko was released from jail after one day," Piotrowski was quoted as saying, adding that many ministry employes had a growing conviction that illegal means would be the only effective action.

Piotrowski called the ministry's leadership "indecisive" and disparaged the government's "policy of concessions" toward the church.

He cited a document he said had been submitted to Interior Minister Czeslaw Kiszczak with proposals for action against Popieluszko. It was turned down, Piotrowski was quoted as saying, with a notation that implied the minister's own sense of helplessness: "I would gladly agree, but. . . ."

Piotrowski and three colleagues on trial at the court in Torun for the murder in October of Popieluszko worked in a section of the Interior Ministry that keeps activist priests under surveillance.

Looking upset, Piotrowski then read a statement in court saying he misled the judges yesterday when he called his attitude toward Popieluszko unemotional.

He went on to vent his frustrations at a string of alleged illegal church actions that he said had gone unpunished and concessions being granted the church.