R. Kelly has come under scrutiny again for his relationship with late R&B singer Aaliyah.

A former background singer for Kelly, Jovante Cunningham, made a shocking revelation during an interview in the Lifetime documentary “Surviving R. Kelly,” alleging that the “Trapped in the Closet” crooner, then 27, engaged in a sexual relationship with Aaliyah when she was just 15.

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“Aaliyah [was] very tomboyish, glasses, braces, no swag,” Cunningham recalls of meeting 12-year-old Aaliyah, who was the niece of Kelly’s then-manager, Barry Hankerson.

“She truly was a beautiful young lady. We used to sneak Aaliyah out of the hotel room and take her all over the place,” Cunningham said. “Those were the good old days, but those are the things that also make you cry.”

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During the interview, which will air as part of a six-part docuseries beginning on Jan. 3, according to People magazine, Cunningham opened up about the feeling she had after learning Kelly and Aaliyah were sexually involved.

“We were out on the road with Aaliyah. On a tour bus, there really aren’t many confined spaces. When you get on the bus there are bunks and so these bunks have little curtains you can pull at night if you don’t want anybody to see you sleeping,” she explained.

“So, it just so happened we were all laying in our bunks and the curtains are open, everybody’s communicating, laughing,” Cunningham continued. “When the [room] door flew open on the bus, Robert was having sex with Aaliyah.”

Singer/actress Aaliyah arrives with her brother Rashad Hasan (R) at the premiere of her new film

R. Kelly reportedly married the late Aaliyah when she was 15 years old. (Reuters)

When pressed to describe exactly what she had witnessed, Cunningham doubled down on her claims adding that it was evident Kelly was having sex with Aaliyah.

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“Things that an adult should not be doing with a child,” Cunningham lamented. “I can’t stress to you how people are still suffering behind things that went on 20 years ago.”

In 1994 reports surfaced that Kelly and Aaliyah had secretly married, and a marriage certificate was made public listing Aaliyah’s age as 18, although she would have been 15 at the time.

Neither Kelly nor Aaliyah ever addressed the nature of their relationship, but his former personal assistant, Demetrius Smith, alleges he was a present witness at the wedding and even obtained false marriage documents for the underage Aaliyah.

“Robert came to me, we were in Miami,” Smith recalled. “Robert said, ‘Man we got Aaliyah in trouble’.” After probing for more information, Smith said he was floored by Kelly’s response; “Robert mentioned to me that ‘I think she’s pregnant’. That broke my heart right there because I really believed him when he said that he wasn’t messing with Aaliyah…Once he told me that, I was at a loss for words.”

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Smith went on to claim, “I was in the room when they got married. I’m not proud of that. I had papers forged for them when Aaliyah was underaged. It was just a quick little ceremony; she didn’t have on a white dress, he didn’t have on a tux. Just everyday wear. She looked worried and scared.”

Kelly’s marriage to Aaliyah was reportedly annulled within the year.

Aaliyah’s career as an actress and singer continued to soar until the Detroit-raised R&B star died tragically in a plane crash in 2001. She was 22.

He was later accused of child pornography after a widely circulated videotape appeared to show him having sex with, and urinating on, a teenage girl. He was acquitted of all charges in 2008 and continued to rack up hits and sell out stadiums around the country.

In recent years, a series of women have come forward to accuse him of everything from sexual coercion to physical abuse.

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That includes parents who said their daughter was being held by Kelly as part of a sex cult, and a woman who said she was in a long-term abusive relationship with him. Kelly and the girl whose parents came forward denied the allegations against him.

Neither reps for Kelly or his music label RCA responded to Fox News’ request for comment on the allegations.

The Associated Press contributed to this report.