WASHINGTON, March 18— Julie Hiatt Steele, a friend of Kathleen E. Willey, released a sworn affidavit tonight, accusing the former White House aide of asking her to lie to corroborate Ms. Willey's account of being sexually groped by President Clinton in the Oval Office.

The affidavit repeats Ms. Steele's earlier contention that in conversations shortly after Ms. Willey's meeting at the White House in 1993, Ms. Willey ''never said anything to suggest that President Clinton made sexual advances towards her or otherwise acted inappropriately in her presence.''

The timing of the release of Ms. Steele's affidavit coincides with this week's concerted effort by the White House to control the damage from Ms. Willey's graphic account on the CBS news program ''60 Minutes'' on Sunday evening of the alleged sexual encounter with the President.

The White House earlier this week released a series of letters from Ms. Willey to the President that portrayed a warm relationship and gave no hint that anything untoward had occurred between them.

Ms. Steele's conflicting account had been generally disclosed previously. But Ms. Willey's characterization of her friend on the ''60 Minutes'' program appears to have been the catalyst for Ms. Steele's decision to release the affadavit, which had been given on Feb. 13 in the Paula Jones sexual misconduct case against President Clinton. [Excerpts from the affidavit, page A18.]

In the television interview, Ms. Willey was asked about Ms. Steele's version of events, and said: ''The White House wanted to try to discredit me and they found a pawn in her.''

A short statement attached to the affidavit tonight calls Ms. Steele ''nobody's pawn.''

Her lawyer, Nancy Luque, said tonight that Ms. Steele ''felt no pressure'' when the President's lawyers initially sought her affidavit as part of their attempt to question Ms. Willey's credibility in the Jones case.

Likewise, Ms. Luque said, the White House did not influence Ms. Steele's decision to release her affidavit. ''It's my view that Julie's story was not adequately represented on 60 Minutes,'' she said. ''That's why I wanted to release the affidavit. That decision was solely mine and Julie's. We took no direction from the White House and won't in the future.''

Ms. Steele and Ms. Willey have known each other for 20 years, but they are now pitted against each other. Ms. Steele's affidavit could also be used to undercut the assertions by the Jones legal team that Ms. Willey's encounter with the President confirms a pattern of sexually harassing female subordinates.

Ms. Willey's account of her meeting with President Clinton first surfaced publicly in Newsweek magazine last summer, a few months after Ms. Willey had approached Ms. Steele for corroboration, according to Ms. Steele's affidavit. It said Ms. Willey had called her to tell her that she had just told Michael Isikoff, a reporter for Newsweek, that the President ''had 'groped' her and pulled at her clothing.'' Ms. Willey wanted Mr. Isikoff to hear that Ms. Steele had learned of these events four years earlier, and asked Ms. Steele to say that Ms. Willey went to her home shortly after the meeting with Mr. Clinton on Nov. 29, 1993, the affidavit states. She said Ms. Willey asked her to ''describe her demeanor as 'upset,' 'humiliated,' 'disappointed,' and 'harassed,' '' according to the affidavit.

''I told Ms. Willey that I could not make such statements because she had not come to my house that day and had never told me of any sexual advances by President Clinton,'' Ms. Steele says in her affidavit. ''She repeatedly assured me that any discussion with Mr. Isikoff would be 'off the record' and that it would be all right if I lied to him. She told me she needed me to do this for her and that she would explain later.''

Mr. Isikoff arrived later that day and Ms. Steele told the story as Ms. Willey had requested.

Three months later, in July, Ms. Steele told Mr. Isikoff that ''Ms. Willey had asked me to lie to support her version of the event and that I had, in fact, done so.''

Ms. Willey's attorney, Daniel A. Gecker of Richmond, did not return telephone calls seeking comment.

The President's lawyers have not only questioned Ms. Willey's credibility, they also have questioned the approach used in the CBS interview.

Tonight, CBS News defended the segment and said that it remained proud despite subsequent revelations that Ms. Willey had been pursuing a book deal.

''We're very happy with the piece,'' said a CBS News spokeswoman, Sandy Genelius. ''We thought it was very strong and eminently fair.''

About 28 million people watched the interview, which was broadcast on ''60 Minutes'' on Sunday evening. Ms. Genelius said that if CBS had known then that Ms. Willey had been pursuing a book deal, the interviewer, Ed Bradley, would have asked her about it.

Ms. Genelius said Ms. Willey would also have been questioned about friendly letters she sent Mr. Clinton. Ms. Genelius declined to comment when asked whether the people at ''60 Minutes'' were disappointed in Ms. Willey for not telling them that her lawyer, Daniel Gecker, and the president of New Millennium Press, Michael Viner, had been talking about a book deal.

Ms. Genelius said the program had generated a larger than average response in letters and telegrams but no unusual outpouring of criticism.

Ms. Willey's pursuit of a book deal, so far unsuccessful, was disclosed on Monday night on the CNN program ''Larry King Live.'' Mr. King interviewed Robert S. Bennett, the President's lawyer, who complained about how ''60 Minutes'' had treated Mr. Clinton and Mr. Bennett himself.

Mr. Bennett said ''60 Minutes'' was ''a program with a point of view'' and that it had withheld some information helpful to the President. Mr. Bennett said Ms. Willey had been pursuing a book deal, a fact confirmed later.

Mr. Bennett also complained that he was made to appear awkward on ''60 Minutes'' by having to look down at a television monitor instead of being questioned face to face.

Ms. Genelius declined to reply directly to Mr. Bennett's complaints. She said again that she thought the program had been ''journalistically entirely responsible.''