A conjoined twin has died after an emergency operation to separate him from his lifeless brother two days after they both survived a high-risk delivery.

Marcos and Mateus, who shared three legs and were joined at the chest, abdomen and pelvis, were moved to a neonatal intensive care unit after their births on Tuesday.

Their mum, 22-year-old receptionist Raylane Siqueira de Oliveira, was said to have been doing well and looking forward to holding the pair in her arms for the first time.

But Marcos died on Thursday after suffering a series of cardiac arrests and overnight it was confirmed his brother had failed to survive an emergency operation to separate him which was brought forward following the first tragedy.

Before trying to save Mateus, paediatric surgeon Zacharias Calil said: 'We did everything we could for Marcos but we were unable to reverse his cardiac arrest.

'He experienced complications through the night and morning.

'He had about four cardiac arrests and the electrocardiogram showed he had a series of complications involving his heart.

'Now we are facing a critical, extremely high-risk situation in order to try to save the baby that survived.

Mother Raylane with her conjoined twins Marcos and Mateus

Doctors working to keep Mateus alive after his conjoined twin Marcos died on Thursday

'Unfortunately there is no other alternative. Let's hope for the best.'

Regional health chiefs confirmed overnight the second baby had died during the operation at the Hemu hospital in Goiania, the capital of the state of Goias in central Brazil.

A Goias State Health Department spokesperson said: 'Even with all the specialised care and intensive support, the second baby also did not survive and passed away.'

Zacharias Calil said in a follow-up message on his Instagram: 'It is with deep sadness that I inform you that, in the early hours of Thursday, one of the conjoined twins suffered successive cardiac arrests and passed away.

'Given the seriousness of the situation, we performed emergency surgery to separate the brothers in an attempt to save the second baby.

'The surgery was technically successful, but despite all the efforts of the medical and neonatal teams, the second newborn also did not survive. I stand in solidarity with the family at this time of immense pain and reaffirm my commitment to medicine based on ethics, responsibility, and humanisation.'

Raylane and her husband Maycon Alex Rodrigues, 30, had travelled from their home in Canarana nearly 400 miles from Goiania for the high-risk delivery.

The twins' father had spoken before the birth about the shock his family felt after discovering his wife was carrying conjoined twins.

He told Brazilian media they only found out during a routine ultrasound in the fifth month of Raylane's pregnancy.