Angelina Jolie and Brad Pitt have denied undergoing fertility treatment to conceive their newborn twins, stating they were fortunate enough to reproduce naturally.

Many gossip rags speculated that the Hollywood power-couple turned to in vitro fertilisation (IVF) to help them expand their brood with twins Knox Leon and Vivienne Marcheline, who were born last month.

But Jolie, 33, tells British magazine Hello!: "If they had been conceived through IVF, we would have been happy to discuss it. But we have been fortunate never to have had fertility problems."

The twins became the fifth and six children to join the Jolie-Pitt clan. They are already parents to adopted kids six-year old Maddox, four-year old Pax, and three-year old Zahara, as well as conceiving their biological daughter, two-year old Shiloh.