Aussie boxing icon Danny Green has said those responsible for the arrest of Ben Roberts-Smith over alleged war crimes should be ashamed of themselves in a fiery social media post.

The former light-heavyweight world champion lashed out after the ex-SAS soldier was charged on Tuesday with two counts of the war crime of murder and three counts of aiding or abetting the same charge.

'Ben Roberts-Smith you have the support of many good people,' Green wrote on Instagram and Facebook.

'A shocking day when a MAN who was trained by the government and paid by the government to to go a war joined by the government, now arrest him in front of his two children, the same man who risked his life daily for that same government's own children.

'SHAME ON EVERYONE WHO HUNG THIS HERO OUT TO DRY.

'You know who you are I hope you feel satisfied.

'Makes me want to vomit and rage at the same time.'

Green finished his message with a rat emoji.

The 53-year-old got plenty of support for his message on Facebook, where it was liked more than 70,000 times, in addition to the 13,000 likes it attracted on Instagram.

Comments like 'He's a hero', 'God bless you Ben Smith' and 'This guy is an Aussie legend and deserves only respect' were typical of the responses the post attracted.

On Wednesday it was revealed that Roberts-Smith will remain in custody for months after being charged.

Australia's most decorated living soldier spent the night in Sydney's Silverwater prison.

He did not appear at a brief, online NSW Bail Division Court hearing on Wednesday, when his case was first heard and his lawyers did not make an immediate application for his release.

They tried instead to have the matter listed for an in-person hearing at the city-centre Downing Centre Local Court for later in the day but conceded that might not be possible.

'We understand that's a bit of a pipe dream,' his lawyer Jordan Portokalli told the bail court.

The judge agreed and re-listed the matter for June 4, meaning the Victoria Cross recipient will remain in custody for at least two months.

The 47-year-old is accused of the murder of unarmed civilians while deployed in Afghanistan between 2009 and 2012 as well as failing to stop members of his unit from killing three others.

While Roberts-Smith's courtroom travails began in 2017 when he unsuccessfully sued Nine Newspapers for defamation, legal experts say his case moving to the criminal realm could be a watershed for war crimes prosecutions in Australia.

The prospect of a criminal trial for alleged offences committed overseas in the theatre of war was almost unprecedented in modern times, former president of the Australian Human Rights Commission Gillian Triggs said.

'It's a very technical area of law and we have had very few examples in Australian national practice that would provide some precedents,' Professor Triggs said.