President Clinton fired FBI Director William S. Sessions yesterday, ending a six-month drama during which the former federal judge refused repeated requests from administration officials to resign.

Clinton telephoned Sessions yesterday afternoon to inform him that he had been fired and then called back several minutes later to remind him that the dismissal was "effective immediately." The president told reporters afterwards that he acted after Attorney General Janet Reno "reported to me in no uncertain terms that he {Sessions} can no longer effectively lead the bureau and law enforcement community" and that he agreed with that assessment.

Clinton, who said it was time to end "the turmoil now in the bureau" and "give the crime fighters the leadership they deserve," is expected to announce today that he has selected federal Judge Louis J. Freeh of Manhattan, a 43-year-old former FBI agent and federal prosecutor, to head the agency. Clinton interviewed Freeh at the White House for two hours on Friday night, press secretary Dee Dee Myers said.

Nearly six years through his 10-year term, Sessions becomes the first director in the 70-year history of the bureau to be fired. Calling a news conference moments after he got the word, Sessions maintained his defiant and proud posture to the end, saying he had led the bureau to "astounding accomplishments" and had refused to submit to pressures to resign because he wanted to preserve the "independence" of the FBI.

"Because of what I would term scurrilous attacks on myself and on my wife of 42 years, it has been decided by others, and now you know by the president of the United States, that I can no longer be as forceful as I need to be in leading the Federal Bureau of Investigation," said Sessions. "I will speak out in the strongest terms about protecting it {the FBI} from being manipulated and politicized both from the inside and out."

Clinton's action ended an agonizing public debate that began last January when a scathing report from the Justice Department's Office of Professional Responsibility (OPR) accused Sessions of numerous ethical lapses. Although a Clinton spokesman immediately described the report as "disturbing" and administration officials concluded within weeks of taking office that Sessions had to be replaced, the White House permitted him to stay on for months -- a delay that senior FBI officials say badly demoralized the bureau and exacerbated an already painful rift between the director and top bureau managers.

Officials said the delay was partly to avoid any criticism that the FBI was being politicized. But that view was challenged by some FBI and Justice officials, who contended privately that the Clinton White House and Reno had displayed what they called a disturbing inability to make a difficult decision.

Clinton said yesterday that he and Reno "agreed that, in the normal course of events, the director of the FBI should not be changed just because administrations change . . . perhaps even especially when there's a change of political party in the White House."

But Clinton said "we cannot have a leadership vacuum" at the agency. Reno, reading from a letter she wrote the president, said she had concluded that Sessions "had exhibited a serious deficiency in judgment involving matters contained in the {OPR} report and that he does not command the respect and confidence needed to lead the bureau and the law enforcement community in addressing the many issues facing law enforcement today."

In what appeared to be a final indignity, moments before the president called Sessions to fire him, Deputy Attorney General Philip Heymann was dispatched to instruct the director on the "ground rules" for the removal of his papers and other possessions, a source said. Sessions was "quite matter of fact. . . . He obviously knew this was coming," said the source.

"So that you will know with clarity the effect of my conversation with President Clinton, I am in the building as a visitor," Sessions said at the start of his news conference. "I am escorted wherever I will be in this building. And I am now a citizen, a private citizen. . . . "

An affable former federal judge from Texas appointed by President Ronald Reagan in 1987, Sessions had long been popular with many members of Congress for what they viewed as his efforts to modernize the bureau, improve cooperation with other law enforcement agencies, and curb abuses that dated back to the days of Director J. Edgar Hoover, who died in office in 1972. Civil rights groups praised Sessions's efforts to bring more minorities and women into the bureau -- an achievement that Clinton said yesterday "will be remembered as the best thing about his tenure."

But Sessions's future was thrown into doubt earlier this year when the OPR report found that he had abused his office by setting up official appointments to justify charging the government for personal travel, improperly billed the FBI nearly $10,000 for a fence around his home, and refused to turn over documents on his $375,000 home mortgage, which investigators said they suspected involved a "sweetheart deal."

The report, based on sworn statements from more than 100 FBI agents, created an uproar within the bureau and was immediately attacked by Sessions and his outspoken wife, Alice Sessions, as the product of an internal cabal of FBI agents and former Bush administration officials out to get him.

Initially, some Clinton administration officials were willing to give the director the benefit of the doubt, expressing some sympathy for his argument that the report was a political "hit" by the outgoing Republican administration. But there was soon a consensus that many of the findings could not be dismissed.

The OPR found, for example, that Sessions bumped security agents off FBI planes and forced them to fly commercially so his wife could accompany him at government expense. FBI aircraft were diverted to pick up Alice Sessions in other cities and FBI vehicles were employed to take her to get her nails done, shop and pick up firewood.

Most troubling to administration officials was the OPR finding of a "sham" arrangement to claim a tax exemption on the value of his chauffeur-driven FBI limousine to and from work. Sessions had received a legal opinion from the chief FBI lawyer that he could use the exemption if he carried a firearm or kept one in the limousine.

The OPR reported that Sessions then obtained a handgun and kept it unloaded in a briefcase in the car. He never took any training, prompting former attorney general William P. Barr on his last day in office to write in a blistering memo to Sessions that the FBI director's use of the exemption "does not even pass the red face test."

Even while Sessions lobbied furiously to retain his job -- recruiting support from civil rights figures Andrew Young and Coretta Scott King, among others -- larger questions were being raised about his judgment. Senior federal law enforcement officials described him as out of touch. Stuart Gerson, a Bush administration holdover who served as acting attorney general until March, said he had recommended that Sessions be fired for reasons that went well beyond the OPR report. "I certainly had no vendetta against the guy," he said. "I didn't think he had the appropriate judgment and scope of knowledge" to perform the job.

Knowledgeable sources said Reno also had concluded even before she took office in March that Sessions "had to go." But the White House had trouble choosing a successor and a series of distractions -- including the political fallout from the FBI tear gas assault on the Branch Davidian compound near Waco, Tex., last April that ended in the deaths of more than 70 of the religious cultists -- forced Reno and the White House to put off the decision several times.

The process came to a climax over the past several weeks when first Heymann and then Reno spelled out to Sessions in a series of meetings that they wanted his resignation. Administration officials said they wanted to give Sessions the opportunity to make a "graceful" exit. But Sessions balked, saying at first he would step down only when his successor was confirmed.

That further alienated the director from top bureau officials who viewed it as a petty attempt to deny Deputy Director Floyd Clarke, who Sessions thought had betrayed him, the opportunity to serve as acting director. Clinton yesterday named Clarke to serve as acting director until a successor is confirmed.

On Saturday morning Sessions was summoned to a meeting with Reno and White House counsel Bernard Nussbaum and was told to quit by Monday or be fired. Sessions again refused and then, upon leaving the Justice Department, tripped over a curb, fell and broke his elbow.

Senate Minority Leader Robert J. Dole (R-Kan.) yesterday criticized the firing, calling it a "potentially worrisome precedent" that might undermine the FBI's independence.

Most other congressional reaction was more positive. Although crediting Sessions with "opening up opportunities for women and minorities," Rep. Charles E. Schumer (D-N.Y.), chairman of the House Judiciary subcommittee on crime, said that Sessions "has lost rank-and-file support and therefore his leadership effectiveness has been severely compromised."

But House Banking Committee Chairman Henry B. Gonzalez (D-Tex.), a longtime friend of the director, said Sessions was "cut down by intriguers in the FBI and the discredited Bush attorney general, who manufactured a crisis, fueled it with whispers and burned up a man of impeccable decency. This is a shameful example of the rawest kind of internal agency political chicanery."