The operation took four and a half hours in total

Correspondents say the procedure exceeded expectations, with surgeons separating Milagros Cerron's legs further than planned, above the knees.

Surgeons said Milagros, dubbed "little mermaid" because of the defect, could move her knee joints independently.

Babies with the condition usually die within days of birth.

One-year-old Milagros is one of only three known survivors of the condition known as sirenomelia.

The surgery had been delayed for three months because of recurring urinary infections and a low red blood count.

The little girl's fate has been followed closely by Peruvians.

'Miracle'

A medical team, led by surgeon Luis Rubio, began operating on the girl at 2230 local time on Tuesday evening (0330 GMT on Wednesday) in a hospital in Lima.

Milagros' father, Ricardo Cerron, who was watching the procedure on monitors, cried as the first incision was made, while mother Sara Arauco put her hand to her mouth.

Milagros celebrated her first birthday a month ago

Afterwards Dr Rubio held up Milagros' legs in a V-shape, displaying stitches stretching from her heels to her inner thighs.

"This surgical intervention has been a true success," he said.

The parents expressed relief at the outcome.

"Yes, this is a miracle," Ms Arauco said, quoted by the Associated Press news agency. Milagros means miracles in Spanish.

"I know, even though I am a sinner, God has paid attention to me, maybe not for my sake, but for my daughter's."

The team, including trauma surgeons, plastic surgeons, cardiovascular surgeons, neurologists, gynaecologists and a paediatrician, spent four and a half hours on the operation.

They had expected to separate the legs only as far as the knees, leaving the thighs for a further operation in three months.

Feet splayed

Most sirenomelia sufferers have severe organ damage and die within hours.

The only person who is known to have survived in the long term is 16-year-old American Tiffany Yorks, whose legs were separated before she was one year old.

Milagros was relatively unharmed, having one good kidney, but only a single channel for her digestive tract and genitals.

She will need operations to correct this, along with her splayed feet, at a later date.

Milagros was born in the mountain city of Huancayo, 200km (125 miles) east of Lima - Peru's capital - to a very poor family.

However, the costs of the operation are being met by the city of Lima, whose mayor is the girl's godfather.

STAGES OF SEPARATION PROCEDURE 1 - Legs are fused together by skin and feet splayed in a V-shape 2 - Saline sacks inserted and gradually filled to stretch the skin 3 - Legs separated, using the stretched skin to cover the wounds 4 - A later operation will rotate splayed feet forward