Australian surgeons have successfully separated conjoined twins in a six-hour operation in Melbourne.

Four surgeons and a team of about 18 people undertook the complex operation at Melbourne's Royal Children's Hospital, attempting to separate the two girls from Bhutan, who were joined from the lower chest to just above the pelvis and shared a liver.

Lead paediatric surgeon Joe Crameri said the operation was actually shorter than expected.

“There weren't any things inside the girls' tummies that we weren't really prepared for,” Dr Crameri told the ABC.

“We saw two young girls who were very ready for their surgery, who were able to cope very well with the surgery and are currently in our recovery doing very well.

“We didn't find surprises, we knew the liver would be connected ... it was divided successfully without any major bleeding.”

The girls are now breathing independently, but the challenge of reconstructing the girls' abdomens remains.

The twins are staying at a property at Kilmore, north of Melbourne, run by Children First Foundation.