Janet Jackson has shot down a long-standing rumour that she secretly gave birth to a baby fathered by James DeBarge in the 80s.

The All For You hit-maker, 55, addresses the bizarre claim in her new self-titled two-part documentary, which begins airing in the US on Friday.

While some claim that the alleged “secret baby” was raised by Jackson’s sister, Rebbie, or brother Jackie, she says that simply isn’t the case.

“Back in the day they were saying that I had a child and I kept it secret,” she says.

“I could never keep a child away from James. How could I keep a child from their father? I could never do that. That’s not right.”

Michael Jackson’s sister went on to reflect how whispers had begun on the set of the TV series Fame in 1984 when she started putting on weight.

“A lot of the kids thought I was pregnant ‘cause I had gained weight and I had started taking birth control pills,” she explained.

“And back then, you could pick up weight taking them, and that’s what happened to me, so that rumour started going around.”

For the conspiracy theorists still not convinced, Jackson’s former Fame co-star, Debbie Allen, 72, corroborates her story, saying: “Where was the baby? Nobody saw a baby. I mean, she was there with us all day, every day. Where was the baby?” she asks.

The scrutiny got so intense that people soon even started pointing fingers at other members of Jackson’s family.

“First they were saying my niece Brandi was my daughter and that I gave her to [my brother] Jackie to raise,” she recalls. “And then because [my brother] Randy’s daughter looks so much like me, they started saying it was Stevanna.”

Jackson and singer DeBarge eloped in 1984 when she was just 18-years-old.

Their marriage was annulled the following year, with Jackson referring to him as a “sweet guy” but citing his frequent drug use that caused their marriage to deteriorate.

Jackson is however a proud mama to five-year-old son Eissa, who she shares with ex-husband, businessman Wissam Al Mana.

Janet, a two-night documentary event, will premiere Friday at pm ET on Lifetime and A&E.