One of the conjoined twins brought to Australia from Papua New Guinea in a bid to save their lives has sadly passed away following an emergency operation.

Tom and Sawong, nearly two months old, underwent a seven-hour surgical procedure at Sydney Children’s Hospital on Sunday.

Tragically, Tom, the more critical of the pair, did not survive the separation, while Sawong was successfully separated.

Medevac pilot Jurgen Ruh, who has been supporting the family, shared that the parents are experiencing a mix of grief and relief.

Sawong remains in critical but stable condition and is receiving intensive care.

He is expected to remain in Sydney for the next few months until the hole in his stomach closes.

“In the first day, he made vast improvements on his medical condition. He is getting better as fast as he can,” Ruh told 9news.com.au.

A funeral is being prepared for Tom. 

The brothers were born attached at the lower abdomen in the remote province of Morobe on October 9 and shared several critical organs, including parts of their liver, bladder and gastrointestinal tract.

Tom also had further issues, including a congenital heart defect and only one kidney. 

Ruh said it was lucky the local hospital could perform the C-section needed to deliver the babies, as only one in 200,000 conjoined twins are born alive.

The brothers were receiving treatment in Port Moresby for several weeks, but the hospital could not perform the separation surgery.

Their parents sought help from Australia, Germany and India.

At the time, their father said: ”Tom and Sawong are fighters and have fought since.”

The parents were in the process of making arrangements for Germany when Tom’s health deteriorated on Thursday, and the twins were rushed to nearby Sydney. 

Specialists from the Sydney Children’s Hospitals Network had helped with the transfer.

Papua New Guinea’s Prime Minister James Marape told reporters he was assured that the Australian government would cover the medical bills.

The twins were assessed in Sydney.

Ruh said specialists believed Tom had very little chance of surviving their separation.