CAIRO, Egypt —  Egyptian doctors on Saturday removed an undeveloped head that was linked to the skull of a 10-month-old girl, an official from the health ministry said.

Ahmed Barakat said surgeons at a hospital in the Nile Delta (search) town of Benha, some 25 miles north of Cairo, treated the baby for craniopagus parasiticus (search), a rare birth defect where a child's skull is linked to the head of an undeveloped twin. The rudimentary head is usually thought to be parasitic.

He said the operation on Saturday lasted about 13 hours and that the girl, Manar, is now in intensive care.

"She is fine and doctors are trying to prevent any complications," he said.

Barakat said a skull reconstruction surgery (search) was also performed. A separate twin sister, Noora, is healthy after initial complications.

Such rare defects occur when an embryo begins to split into identical twins but fails to complete the process, leaving an undeveloped conjoined twin in the womb.

The twin sisters were born on March 30 last year.