A major surgery to separate Bhutanese conjoined twin girls in an Australian hospital has been successful, doctors involved in the procedure said on Friday. 

A team of 25 surgeons, anesthesiologist, clinicians and nurses at the Royal Children’s Hospital were involved in the six-hour procedure to separate 15-month-old Nima and Dawa Palden who were joined at the torso and shared a liver. 

Images shared by the hospital in Melbourne show the girls lying on separate beds for the first time.

"It is a relief and it’s also a joy," said Joe Crameri, the chief paediatric surgeon who led the operation, after the procedure.

The sisters are in recovery and breathing independently following the surgery, he said.

One of the mains concerns was the possibility the two shared a bowel.

"We were very fortunate in that there wasn’t any significant bowel attachment and while it was all swimming next to one another it wasn’t actually connected in any major way," he told reporters. 

"And really the main challenge today, as we thought was getting the abdomen reconstructed so that both areas were closed over." 

Surgeons were also able to divide the liver, he said. 

"There will be challenges over the next 24 to 48 hours as with any surgery," Crameri said. "We feel quietly confident that we will have a good result and that is what I have just told mum upstairs."

Crameri said a team of doctors and nurses "will closely monitor things for a while to ensure that we achieve our aim." 

He also said they are hopeful the twins will not have to spend time in the Intensive Care Unit (ICU). 

Conjoined twins are very rare - about one in every 200,000 births, with about half of delivered stillborn.

Before the surgery the twins could face each other, but could not sit down together and had to lie down. They could stand if they do so at the same time. 

The twins arrived with their mother from the landlocked Himalayan kingdom of Bhutan last month. 

The marathon procedure to separate them was postponed three weeks ago at the last minute. The twins then received additional nutritional support, physiotherapy and other health assistance. 

The state Victorian government will cover the 350,000 Australian dollars (255,000 US dollars) cost of the operation.

The planned operation comes nine years after the same hospital successfully separated Bangladeshi sisters Trishna and Krishna in a ground-breaking 38-hour-long operation.

They are now living in Adelaide in South Australia.