Surgeons operated on a 2-month-old Pakistani girl Tuesday to remove two fetuses that had grown inside her while she was still in her mother's womb, a doctor said.

The infant, who was identified only as Nazia, was in critical condition following the two-hour operation at The Children's Hospital at Pakistan Institute of Medical Science in the capital, Islamabad, said Zaheer Abbasi, head of pediatric surgery at the hospital.

A doctor pumps oxygen to two-month-old Pakistani girl Nazia after she went through a major surgery at a local hospital in Islamabad, Pakistan, Tuesday, March 28, 2006. [AP]

Abbasi, the chief doctor who led the operation, said the case was the first he was aware of in Pakistan of fetus-in-fetu, where a fetus has grown inside another in the womb.

"It is extremely rare to have two fetuses being discovered inside another," Abbasi told The Associated Press, adding that he did not know what caused the medical abnormality. "Basically, it's a case of triplets, but two of the siblings grew in the other."

The baby comes from Abbotabad, about 30 miles north of Islamabad. She is the fifth child of a woman in her 30s, who was at the hospital to be with her daughter. Her father works in the Arabian Gulf.

Abbasi said surgeons removed the two partially grown fetuses, totaling about two pounds, that had died at about 4 months.

Other fetus-in-fetu cases have been reported elsewhere in the world. A report in a June 2000 issue of the U.S. journal Pediatrics called such occurrences rare and estimated their rate at about 1 per 500,000 births.