LONDON – As he acknowledged to a court in London this week, Roman Polanski was, in his younger days, a libertine and rake who freely engaged in casual sex, sometimes with more than one woman at a time.

But on no account, Mr. Polanski declared, did he try to seduce a beautiful Swedish woman in 1969 while en route to the funeral of his wife, Sharon Tate, soon after her brutal murder by followers of Charles Manson in California. Nor was it true, he added, that as part of part of his seduction technique, he placed his hand on the woman’s thigh and murmured, “and I will make another Sharon Tate out of you.”

Details of the putative seduction were reported by Vanity Fair magazine in 2002. Monday’s testimony came on the opening day of a libel case that Mr. Polanksi, the director of films including “Rosemary’s Baby,” “Chinatown” and “The Pianist,” brought against the magazine.

“It is obvious that it’s not true,” he told the court, speaking of Vanity Fair’s assertions. “I don’t think you could find a man who could behave in such a way, but I think it was particularly hurtful as it dishonors my memory of Sharon.”

In a highly unusual arrangement, Mr. Polanski was testifying from France, where he lives, via a live video link to the London courtroom. The director, now 71 and married to the French film actress Emmanuelle Seigner, is a fugitive from American justice, having fled the country after pleading guilty to the statutory rape of a 13-year-old girl in 1977.

Because Britain has an extradition agreement with the United States, Mr. Polanski was afraid, he said, that if he went to London he would be arrested and sent back to the United States.

The Law Lords, Britain’s highest court, ruled in February that Mr. Polanski could bring the case – Polanski v. Condé Nast Publications Ltd. – without appearing in person. He is the first plaintiff to do so in such a case in Britain.

Vanity Fair is sold in both the United States and Britain, but Britain’s libel laws are weighted against defendants and tend to make it far easier for plaintiffs to win cases here than in American courts.

The article in question, by A. E. Hotchner, wasn’t about Mr. Polanski; its subject was the New York restaurant Elaine’s. The passage about him was buried deep inside.

Mr. Hotchner quotes Lewis Lapham, the editor of Harper’s Magazine, as saying that Elaine’s famous customers are spectacularly unimpressed by one another and that the only time he had ever seen “people gasp” in the restaurant was in August 1969 when Mr. Polanski visited the restaurant while on his way to Hollywood for Miss Tate’s burial.

Mr. Lapham was sitting at a table with some friends, including “the most gorgeous Swedish girl you ever laid eyes on,” he is quoted as saying.

Mr. Lapham continued, according to Mr. Hotchner’s article: “Polanksi pulled up a chair and inserted himself between us, immediately focusing his attention on the beauty, inundating her with his Polish charm. Fascinated by his performance, I watched as he slid his hand inside her thigh and began a long, honeyed spiel which ended with the promise, ‘And I will make another Sharon Tate out of you.’ ”

On the witness stand, Mr. Polanksi called the account “all lies.”

“It’s not the way I behave as far as my sexual life is concerned,” he said. “I still had some honor. I still have some now.”

His lawyer, John Kelsey-Fry, told the court that despite Mr. Polanski’s “somewhat laissez-faire attitude to casual sex” as a younger man, the case was not about his general morality but about the incident in question.

Beth Kseniak, a spokeswoman for Vanity Fair, said that the magazine stood by its account of the events at Elaine’s, with one small exception. The incident described by Mr. Lapham, Ms. Kseniak said, took place after Tate’s funeral, not before. But, she said, “our defense is that the substance of the story is true.”

Mr. Polanski’s lawyer plans to call the actress Mia Farrow, who is expected to testify that she met Mr. Polanski at Elaine’s that month and that all he could talk about was how upset he was at the deaths of Tate, who was eight months pregnant, and the couple’s unborn baby.

For its part, Vanity Fair is expected to call Mr. Lapham as a witness. Ms. Kseniak said that Mr. Lapham stands by his account of what happened in the restaurant.