Rapper Wyclef Jean knew Lauryn Hill's first child wasn't his as soon as he laid eyes on the newborn - because the baby's skin colour was too light.

The Haitian-born hip-hop star has opened up about his affair with his former Fugees bandmate in his new memoir Purpose: An Immigrant's Story, in which he accuses Hill of misleading him about the paternity of her son.

In the book, he writes, "In that moment something died between us. I was married and Lauryn and I were having an affair, but she led me to believe that the baby was mine, and I couldn't forgive that. She could no longer be my muse. Our love spell was broken."

Wyclef has now opened up about the moment he realised he was not the kid's dad, after setting sight on the tot for the very first time moments after Hill gave birth.

He tells U.S. talk show host Wendy Williams, "I was there, I came to the hospital (and) I just knew. When I looked (at the child)... all babies don't look alike, that was a yellow baby, that wasn't my baby."

The child's biological father was actually Bob Marley's son, Rohan.