JERUSALEM, OCT. 30 -- A special investigative committee reported today that agents of the Shin Bet internal security service routinely used "physical pressure" to extract confessions from Arab suspects and then lied about those methods in court, but it recommended that no agents be prosecuted for these practices.

The panel's report says, "This evil must be pulled out by the roots." But its apologetic tone and lack of punitive recommendations are likely to be seen by many as tacit vindication for the troubled agency.

The report seemed to reflect a consensus among Israelis that while abuses of power were unfortunate, the Shin Bet deserves public support because of its complicated task of preventing terrorism and enforcing security laws in the occupied West Bank and Gaza Strip.

Prime Minister Yitzhak Shamir indicated as much today when he told reporters that while he had not yet read the report, "I don't think it will have a negative impact on the morale of our security services. I know very well that they are doing a very professional job and they will continue to do it."

The public section of the report -- released by Shamir's office on the eve of the Jewish Sabbath in an apparent attempt to blunt its impact -- described a 16-year-long abuse of Israel's judicial system that it said was either ignored or actively encouraged by senior officials of the agency, which is the country's equivalent of the FBI.

The "distressing and regrettable" result, the report said, was that the agency "permitted itself to violate the law systematically and over a long period of time by agreement, approval and even encouragement of perjury in the courts."

While the panel condemned the abuses, it concluded that such transgressions had stopped and recommended that "the national security interest dictates the cessation of criminal procedures" against those agents responsible. It also endorsed the use of "nonviolent psychological pressure" against suspects and added that when this was not sufficient, "moderate physical pressure may be used."

The panel did not specify what it meant by either term, but the secret section of the report, submitted to Shamir, is expected to contain detailed guidelines for interrogations and other practices.

The commission also said it had found no evidence that the prime minister, to whom the agency reports directly, knew of the Shin Bet's abuses.

In the past, according to testimony in several court cases and admissions by agents, Shin Bet officers have routinely beaten, kicked and punched suspects, deprived them of sleep, doused them with cold water and threatened them with violence against their families.

Agents have justified these practices by saying they were necessary to extract information quickly in order to prevent prospective terrorist actions. They said they then lied in court so that suspects they believed to be guilty would not go free because of tainted confessions. It is estimated that confessions are crucial to at least 80 percent of convictions in security cases in the occupied territories.

The agency has been under fire since 1984 when it was revealed that senior members clubbed to death two captured Palestinian bus hijackers, covered up the killings and, when exposed, sought to shift the blame first to a senior Army officer and then to the prime minister. The head of the agency, Avraham Shalom, was forced to resign along with several senior aides, but he and 10 other agency officials received presidential pardons to save them from prosecution.

Last May, the Israeli Supreme Court ruled that Izat Nafsu, a loyal Moslem Army lieutenant, had been framed by Shin Bet agents and unjustly sentenced to 18 years in prison after being mistreated and beaten into a tainted confession.

Shin Bet officials, fearing their operatives would face criminal charges for assault and perjury, pressed instead for a judicial inquiry, arguing that procedures such as those used on Nafsu had been standard practice for years.

The three-member commission, appointed by Shamir and headed by retired justice Moshe Landau, confirmed that the system of "pressure" -- it did not use the word "torture" -- and subsequent perjury began with Israel's 1967 occupation of the West Bank and Gaza Strip and took firm hold by 1971.

The panel, which heard 42 witnesses, including the present and several former prime ministers, found that by 1982 the system was so deeply rooted that the unnamed Shin Bet chief of that period gave it full endorsement.

The committee cited a written protocol dated Sept. 6, 1982, in which the agency's chief and the head of its investigations division agreed that when the question of a confession's validity came up in court, agents "will deny the use" of illegal methods of interrogation and claim that the methods used were "acceptable under the procedures of the prison."