CALCUTTA, India - A chicken has gone through a rare, spontaneous sex change in eastern India, a veterinarian said Thursday.

The bird laid eggs six months ago -- and some hatched -- but it later began to grow a rooster's comb, said Partha Sarathi Ghose, a veterinarian at West Bengal state's Animal Husbandry Department, quoting the bird's owner.

Earlier this week Ghose and a team of experts visited the village of Kamat-Chengrabanda where the incident occurred.

Ghose said the bird had undergone a process of natural sex change.

"Sure, it's rare,'' the veterinarian said, adding that owner Haziruddin Mohammad has called the incident a miracle and refused to hand over the bird to the Animal Husbandry Department.

"Every once in a while you hear a story about a hen that changed into a cock. Such stories are often met with skepticism, but sex reversals do, in fact, occur, although not very frequently,'' says a 2000 report published by the University of Florida's Institute of Food and Agricultural Sciences.

The study said spontaneous sex reversals can result from damage to one ovary.

It said that there are reports of some such birds fathering offspring, but that most never do.