An Australian couple who abandoned a boy born in a surrogacy deal in India were repeatedly told the child would be left stateless, new evidence shows.

Documents reveal the shocking details of the case that saw a couple return to Australia with a baby girl while leaving her twin brother behind.

Australian government officials had full knowledge of the startling ordeal, according to documents obtained the ABC.

An Australian couple who abandoned a boy born in a surrogacy deal in India were repeatedly told the child would be left stateless, new evidence shows (stock image)

The FOI documents reportedly show staff at the Australian High Commission in India and Department of Foreign Affairs and Trade were aware the couple was from New South Wales, where it is illegal to enter into international surrogacy arrangements.

Conversations between the Australian High Commission in New Delhi and Government officials in Canberra detail how the couple travelled to India in late 2012 and seeked citizenship for a baby girl but told consular staff they would be leaving her twin brother behind because they could not afford him.

The couple reportedly told staff they wanted a baby girl to 'complete their family'.

The Australian man told consulate staff he would be giving the boy to some friends in India 'who were unable to conceive a child', according to the report.

The couple was told the boy would be left stateless if they followed through on plans to abandon him, because India does not recognise surrogate children as citizens.

Documents reveal the shocking details of the case that saw a couple return to Australia with a baby girl while leaving her twin brother behind

'If the parents do not apply for Australian citizenship for the child, the child will be stateless in India... our ability to provide assistance to a non Australian citizen is limited,' a DFAT email in December, 2012 said.

There were also fears last year that the boy may have been sold.

Chief Justice of the Family Court, Diana Bryant, said consular staff had told her of their concerns.

The FOI documents reportedly show staff at the Australian High Commission in India and Department of Foreign Affairs and Trade were aware the couple was from New South Wales, where it is illegal to enter into international surrogacy arrangements

'They expressed to me that in fact money had changed hands, and if that's true, then that's basically trafficking children,' she said.

'We're commoditising children and that's a huge concern. It's in breach of all sorts of human rights conventions – it's a criminal offence in many places.'

If money was paid, any adoption would be deemed invalid under India's Hindu Adoption Act.

The Indian case is similar to the recent baby Gammy case, who was born in Thailand to a surrogate mother and whose Australian parents only brought back his twin sister.