Sydney  - The second of the Bangladeshi conjoined twins separated in Australia is out of an induced coma, doctors said Saturday.

Trishna was the first to be woken and a statement from Melbourne's Royal Children's Hospital on Saturday said her sister, Krishna, had now gained consciousness.

Scans of the 2-year-old orphans showed no brain damage. Last week's 31-hour operation was declared a success and optimism prevails that both girls could make a full recovery.

Before surgery, doctors estimated that the chances of both twins surviving the marathon procedure were only 25 per cent, and that each had a 50-per-cent chance of avoiding brain damage.

Plastic surgeon Tony Holmes, who was in the team crafting new skulls made of bone fragments and plastic parts, said Krishna had more extensive neurosurgery and had experienced more changes to her body than Trishna.

"It was hard to tell just how much of the brain tissue was crossing over," he told national broadcaster ABC "But during the operation it became apparent that the majority of the difficulty was on Krishna's side."

The twins, who whose third birthday is next month, were left in a Dhaka orphanage at birth. They have spent their last two years in Melbourne and their parents want them to stay in Australia.

The chance of them both making a full recovery is still estimated at only 25 per cent, but without the operations they would have died within the year. (dpa)