CHICAGO - A prosecutor in the child-pornography trial of R. Kelly warned jurors yesterday that they would have to watch a videotape depicting an "underage child performing sex acts that you have never seen before."

"A child doesn't choose to be violated and placed on a videotape, a videotape that will live on forever - long after this child becomes an adult," Cook County prosecutor Shauna Boliker told jurors as opening statements got under way in the R&B singer's long-delayed trial.

Kelly, 41, is accused of videotaping himself having sex with an underage girl who prosecutors maintain was as young as 13 when the tape was made between Jan. 1, 1998, and Nov. 1, 2000.

Defense attorneys, however, told jurors in their opening statements that Kelly isn't the man on the tape and called the video's origins into question. The defense also told jurors that the female that authorities allege is depicted on the tape isn't that person at all.

That's a claim that's also been made by the 23-year-old woman who prosecutors say was a minor at the time of the taping. She denies she's the girl on the video.

Kelly sat grim-faced during the proceedings, intently studying the jurors across the courtroom as he hunched forward in a leather-backed chair.

The trial has been delayed repeatedly since the tape was mailed to the Chicago Sun-Times in 2002. The newspaper turned it over to authorities, and Kelly was indicted later that year.

The singer, who has pleaded not guilty, faces up to 15 years in prison if convicted.

Boliker repeatedly referred to the female depicted in the tape as a "child" and referred to Kelly by his birth name of Robert Kelly. She alleged that the singer took advantage of the inherent trust children place in adults, and that the female on the tape performed acts that Kelly "commanded" her to perform.

The videotape, she said, is "child pornography that was created, staged, produced and starred in by the defendant that sits before you, Robert Kelly."

Boliker's opening statement lasted more than 30 minutes. Jurors then listened to one of Kelly's defense attorneys, Sam Adam Jr.

Adam told jurors that the videotape is "at best a copy of a copy of a copy," and that Kelly isn't the man on the tape.

"Not a single witness can tell you that is him on the tape," Adam said. He also said the FBI could not identify the man on the tape as Kelly.

What's more, he said, Kelly has a "significant" mole in the middle of his lower back that has been there since childhood. But he said the man on the tape did not have the mole.

"There is no mole on his back," Adam said. "Robert isn't that man on the tape." *