Selena Gomez demanded the truth from boyfriend Justin Bieber seconds after false rumors he'd fathered a lovechild surfaced on the internet.

The "Baby" hitmaker was embroiled in controversy in November when Mariah Yeater, then 20, alleged she had fallen pregnant by him during a backstage romp at one of his concerts in Los Angeles in 2010.

Bieber voluntarily underwent a DNA test to prove Yeater was lying, and her paternity lawsuit was later dropped.

But Bieber reveals his girlfriend Gomez wasn't immediately convinced the accuser was making up stories and called him as the scandal broke, seeking his reassurance the baby drama wasn't true.

He tells The Sunday Times Magazine, "She was like, 'Do you see what they're saying on the internet?', (and) I was like, 'Yeah.' She was like, 'So...', I was like, 'No, it's not true.' (She said) 'Okay, thank you, bye!'. That was it. She trusts me."