Doctors there told them she is not an albino.

"She doesn't look like an albino child anyway - not like the ones I've seen back in Nigeria or in books, " Ben told The Sun. "She just looks like a healthy white baby."

Ben added: "Of course, she's mine. My wife is true to me. Even if she hadn't been, the baby still wouldn't look like that.

"We don't know of any white ancestry. We wondered if it was a genetic twist. But even then, what's with the long curly blonde hair?"

Professor Bryan Sykes, head of Human Genetics at Oxford University, said: "In mixed race humans, the lighter variant of skin tone may come out in a child - and this can sometimes be startlingly different to the skin of the parents.

"This might be the case where there is a lot of genetic mixing, as in Afro-Caribbean populations. But in Nigeria there is little mixing."

He said that both parents would have needed some form of white ancestry for a pale version of their genes to be passed on.

"The hair is extremely unusual, " Prof Sykes said. "Even many blonde children don't have blonde hair like this at birth."

Some form of unknown mutation was the most likely explanation, he added.

The couple, of Woolwich, south London, have two other children, four-year-old Chisom and sister Dumebi, two.

Mum Angela, 35, told the paper: "Nmachi's colour doesn't matter. She's a miracle baby. But still, what on earth happened here?"