Nicole Kidman is "very interested" in fostering a child

She said: "I'm one of the few people in the world who has experienced so many different forms of [becoming a mother].

"But I haven't had the child from a donor egg. I haven't also been a foster mother and I'm very interested in that... But I did foster a child that I met through school, an aboriginal boy."

The 49-year-old actress insisted she feels exactly the same way about her adopted children as she does about her biological daughters.

Speaking to BBC Radio 4's 'Woman's Hour', she said: "I can only speak for myself. Once the bond is formed, the bond is formed. The bond is what they emphasise in terms of any sort of maternal role.

"It's why when you give birth, they go, 'Quickly hold your baby, smell your baby.' As soon as that bond is formed, that's it. You know that feeling of you would die for that child."

Despite previous claims Nicole has a strained relationship with her older kids because of their Scientology faith, she refused to be drawn on the gossip and simply insisted she has "unconditional love" for her offspring.

She said: "I don't discuss any of it. I don't discuss any of my children in terms of their privacy. All I say is that there's unconditional love. I try to keep things simple."

The 'Moulin Rouge!' actress recently admitted she hasn't given up hope of having another biological child.

She said: "I still have the faintest hope that something may happen to me this year. Keith and I would love to have more babies.

"My grandmother gave birth to my mother at 49! I would be beyond happy and just welcome it with open arms. Children are the joy of my life."