London, Nov 17 Surgeons at Melbourne's Royal Children's Hospital have separated conjoined Bangladeshi twins, who were joined at the top of their heads and shared blood vessels and brain tissue, after a marathon 27-hour long surgery.

Leo Donnan, the head of surgery at the hospital, described as "surreal" the moment the twins - Bangladeshi orphans Krishna and Trisha - finally were separated at 11:00 am AEDT, reports The Times.

"It's something which for two years has been planned," Donnan told reporters shortly after they were separated.

"Everyone has known these girls as one with their individual personalities, so to see them as separate human beings is a pretty amazing moment," he added.

The girls were brought to Australia by the Children's First Foundation (CFF).

They have undergone a number of procedures over the past two years to prepare them for the marathon procedure for which doctors had given only a 25 per cent chance of complete success.

"This is a once-in-a-lifetime operation that teams would do," Donnan said.

"For the hospital, it is an historic moment and for the girls, an even more historic moment," he added.

However, despite the success of the separation, Donnan said there is "still a long way to go" until the girls can be stabilised and eventually released from the ICU. (ANI)