Siamese twins Saba and Farah are blissfully unaware of the tough decision their father Mohammed Shakeel will soon have to take on whether to go in for a surgery to separate them.

A day after a team of doctors at Indraprastha Apollo Hospital here announced the possibility of successfully separating them, the 10-year-old twins were busy watching television while their father weighed the options.

"We are going back to Patna today (Wednesday) for Ramzan and after consulting our family and relatives, we will take a final decision about the operation," Shakeel told.

"After the successful angiography on Monday, we are hopeful of seeing our kids separately. There is a certain degree of anxiety but we have full faith in the doctors," said Shakeel, a shopkeeper from Bihar's capital Patna, trying to cope with all the information given to him.

The twins have become the cynosure of the media following an offer by Sheikh Mohammed bin Zayed Al Nahyan, the crown prince of Abu Dhabi, to bear all expenses for the operation estimated to cost over $1 million. The prince made the offer after seeing a picture of the twins in an Indian newspaper.

Mohammad Tamanna, an elder brother of the twins, said: "The doctors have explained everything to us but a final decision will have to be taken by my father. After Ramzan, he will take a decision."

Ramzan, the Islamic holy month of fasting and penance, begins Thursday.

Siamese twins, also known as conjoined twins, are rare and more than half of them do not survive beyond a few hours after birth, experts say.

What gives hope in the case of Saba and Farah is that over the past decade there have been several successful cases of Siamese twins having survived and thrived after separation.

Mukul Varma, senior consultant neurologist at Apollo Hospital, said: "Unlike in the case of Iranian twins Ladan and Laleh Bijani, where the separation was carried out in one go, leading to massive blood loss and death, we plan to go in for surgery in steps.

"Depending on the response and results, each stage will be decided on," said Varma, who is heading the team of over 20 senior consultants involved with the case.

Benjamin Carson, director of paediatric neurosurgery at Baltimore-based Johns Hopkins Children's Centre, who was called in by the Apollo Hospital as a consultant to what is going to be a major surgery involving months of preparations, said: "Having analysed their medical reports, we can say with a certain degree of confidence that the operation is possible."

In 1987, Carson conducted the world's first successful operation to separate a pair of conjoined twins.

The first step after getting Shakeel's permission would be to build three-dimensional models of the twins' skulls to carry out virtual or mock surgery on a computer workstation. This is expected to take about three months.

Among the challenges to be resolved by doctors is the fact that Saba and Farah have a common blood drainage system for their brains. This will be tackled by creating an alternate channel for one of the twins, a procedure that may take more than two months and carries some risk.

Prior to the main surgery of separating the skulls, doctors plan to use for the first time what is called a "distracting" procedure whereby the skull membrane would be sliced to create a five-millimetre gap.

"Over a period of time the brain fluid will move between the two brains and start to separate them, making it easier to physically separate them," said Varma.

"At every stage we will keep assessing the progress. Between each stage there will be a gap of two to three months. At any stage the procedure can be stopped without endangering the life of the twins," the neurologist said.

It is only after the skulls have been separated that the twins will undergo another surgery for transplanting one of Farah's kidneys in Saba, who has no kidney.

Prior to the main surgery, Saba will be put on peritoneal dialysis and after she has stabilised, she will receive the transplant.

Ahead of the surgery, the Hospital is awaiting the arrival of a high-resolution MRI machine that will aid the complex procedure.