A pair of eight-day-old conjoined twin girls were separated by doctors in Switzerland. The babies are believed to be the youngest ever to be successfully parted. Lydia and Maya were born on 2 December "extensively conjoined on the liver but had all vital organs," according to the Inselspital hospital in the country's capital, Bern.

Describing the 10 December operation as a "medical sensation" they said it was "the first successful operation of such small conjoined twins in Switzerland and possibly even worldwide." The girls were doing well, the hospital said in a statement, adding that "in the past 30 years conjoined twins were only born and successfully separated two other times in Switzerland."

Doctors were forced to perform a Caesarean section on their mother because of the state of her health, the hospital said. A third child was also born fully separate and healthy, they added.

Lydia and Maya weighed just 2.2kg (4lb 14oz) together and "had great problems," the hospital said.

Because a "great amount of blood flowed from one child to another through the liver", one baby had extremely high blood pressure.

"The other child did not receive enough blood and had blood pressure that was too low," it added. In order to save the children, after a good week, a team of doctors decided to risk the surgical separation.

The operation is said to carry a 1% chance of success, according to reports in Swiss media. Doctors had originally planned to separate them when they were several months old, but brought the operation forward when they both suffered a life-threatening condition.

Praising his staff, Steffen Berger, head of the hospital's Department of Paediatric Surgery said: "The perfect teamwork of physicians and nursing personal from various disciplines were the key to success here."

He added: "We are very happy that the children and parents are faring so well now."