The girls were operated on by a team of specialists led by paediatric surgeon Professor Agostino Pierro.
He said: "In this case, the twins were joined by the abdomen at the level of the umbilicus and shared part of the intestine.
"The operation to separate the twins had to be performed as an emergency because of an intestinal blockage.
"We are delighted with the outcome of the operation. The babies will need further treatment in the future, but we expect that they will both be able to lead happy and normal lives."
In their first television interview parents Rosie and Ruby Formosa speak of the "dangerous" way their twins were joined at birth.
A mother has described her joy after a successful operation to separate her conjoined twins.