For years, critics have accused independent counsels of conducting costly and ever-expanding investigations that have resulted in the criminalization of American politics.

But even some of those most skeptical about the 1978 law that established the counsels said this week that Whitewater independent counsel Kenneth W. Starr seemed on firm legal ground when he sought and received judicial permission to expand his probe into whether President Clinton urged a 24-year-old former White House intern to lie in sworn testimony.

Surrounded by a huge crowd of jostling reporters outside his downtown Washington office yesterday, Starr avoided comment on the probe's substance. But he defended -- three times -- the propriety of his expanded investigation.

"We at all times satisfy ourselves through very careful analysis that we are acting properly within our jurisdiction," Starr said. "We are mindful of both the Justice Department and the {three-judge panel's} role in determining jurisdiction, and we are very keenly sensitive" to that issue.

Starr also noted that Attorney General Janet Reno and the three-judge panel that oversees independent counsels have granted him several previous expansions of his original 1994 mandate to investigate the Whitewater land deal in Arkansas. Those broadened investigations -- into such matters as the White House travel office firings and the alleged misuse of FBI files by White House personnel -- are ongoing, Starr said.

But those expansions have also prompted President Clinton's defenders to complain about Starr "mission creep." Attorney Abbe D. Lowell, a Democrat, said he is worried by the many new incarnations of Starr's investigation. "It seems that he has become an independent counsel to get the president, not an independent counsel to get the facts," Lowell said.

Adding to the independent-counsel criticism during President Clinton's administration, the outside attorneys prosecuting former Clinton housing secretary Henry Cisneros and ex-agriculture secretary Mike Espy have been harshly criticized for going beyond the scope of their initial charges, targeting peripheral players and spending too much time and money investigating offenses that, even if proven, might not warrant the effort.

This latest Starr inquiry was kicked off when Starr received secretly taped recordings in which ex-White House aide Monica Lewinsky said Clinton and Washington lawyer Vernon E. Jordan Jr. urged her to lie to attorneys in the Paula Jones sexual harassment case. Starr received approval from Reno and the three-judge panel last Friday to broaden his probe.

In his secret application to Reno last week, sources said Starr justified the expansion by pointing out that his team already is examining allegations that Jordan, a close Clinton friend, tried to buy the silence of former Justice Department official Webster L. Hubbell by lining up consulting jobs for him. Starr, the sources said, asserted the new allegations that Jordan urged Lewinsky to lie by denying she had a sexual affair with Clinton, and that Jordan was helping her find work in New York, are closely related to the guts of the earlier investigation of Jordan.

"If Vernon Jordan's actions are a subject of the new investigation, then that seems reasonably related to the pre-existing probe," said Terry Eastland, a former Reagan administration Justice Department official and a harsh critic of the independent counsel law. "I'm not troubled by this at all."

"Starr did precisely what any good prosecutor would do," said Joseph E. diGenova, a former independent counsel himself who is a bitter critic of the use of such independent prosecutions.

But Clinton lawyer Robert S. Bennett was critical of Starr's actions. "We should think long and hard before we have sting operations involving a sitting president," Bennett told reporters yesterday.

Alexia Morrison, who was an independent counsel in the 1980s examining a Justice Department official for allegedly misleading congressional testimony on environmental records, said Reno's approval of Starr's request insulates Starr from criticism.

"The hoo-ha {over whether Starr properly expanded his probe} has been settled by the one person who holds the key to whether an independent counsel should be appointed, and that's Reno," Morrison said. The new probe apparently centers not on whether Clinton had an improper sexual relationship, but on whether "the chief law enforcement officer in the land was screwing around with the justice system," she said.

DiGenova, who as an outside counsel examined the Bush-era State Department's improper search of then-candidate Bill Clinton's passport records, is a leading critic of the 1978 independent prosecutor law, calling it "a constitutional monstrosity and a legislative disgrace" because it strips the Justice Department of its prosecutorial functions.

But diGenova said Starr did the right thing on Jan. 12, when an erstwhile Lewinsky friend, Linda R. Tripp, approached him with tapes she had surreptitiously made of Lewinsky allegedly describing her dalliances with Clinton and his appeals that she lie about it. Starr then asked the FBI to place a wire on Tripp and have her talk to Lewinsky. DiGenova said there was no way Starr could have gone to the attorney general for approval of an investigative expansion based on tapes secretly made by a non-law enforcement figure.

Had Starr gone with Tripp's tapes, Reno and the judges could have questioned the tapes' authenticity, diGenova said.

Starr need not have sought Reno's approval of his request because of a 1996 court ruling allowing independent counsels to bypass the Justice Department in seeking expansions into areas they consider related. But he wanted her approval for political reasons, to discourage Democrats from crying foul, said a source close to the Starr probe. Staff writer Ruth Marcus and researcher Colleen Allen contributed to this report. CAPTION: Whitewater independent counsel Kenneth W. Starr, facing a horde of reporters outside his office in downtown Washington, defends expanding his investigation.