Former Australian soldiers are playing a key role in a Saudi-led military onslaught against Yemeni rebels, in a conflict which human rights groups are alarmed by.

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The group of ex-Australian Defence Force (ADF) members includes a one-time special forces commander, who is in charge of an elite military unit in the United Arab Emirates.

Retired Major General Mike Hindmarsh is the commander of the UAE's presidential guard and reports directly to Crown Prince Mohammed bin Zayed al-Nahyan.

The UAE is among a group of Gulf States who accuse Iran of backing Houthi rebels in Yemen, and have formed a military coalition to push back.

University of Sydney international security expert Dr Sarah Phillips said the conflict was widely stated as being a proxy war between Saudi Arabia and Iran.

"The Saudi-led military intervention has been going since late March of last year and that forms the major component of the international angle to this conflict," she said.

Human rights groups are increasingly worried about the growing civilian casualties in the bloody Yemeni conflict.

Last year Amnesty International called for a suspension of arms exports to members of the Saudi-led coalition after reporting what they described as "damning evidence" of war crimes in Yemen.

"The Saudi-led coalition is behaving in a way that's reckless at best, at best," Dr Phillips said.

"They have bombed an extraordinary number of hospitals, schools — all manner of civilian institutions and infrastructure. Just recently we've had cluster bombs which have previously been used elsewhere in the country being dropped in the capital city of Sana'a."

Australians helping to 'improve standards'

But defence sources have told the ABC the Australians are helping to improve the standards of the Gulf forces.

John Blaxland from the Australian National University's Strategic and Defence Studies Centre says it is not unusual for ADF members to accept higher salaries in foreign militaries — or from private military contractors.

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"Actually donning the uniform of another country in the Middle East — that's a more recent phenomenon," Dr Blaxland said.

"Major General Mike Hindmarsh is the most prominent example of that, something that's grown since then with a number of other participants who've joined General Hindmarsh in supporting the United Arab Emirates armed forces."

Dr Blaxland admitted the Yemeni situation presents a vexed situation for the Australians.

"In looking at the talk of human rights abuses, or breaches of international standards we need to look at the other side of the picture and see what could have been the case had Australians not been involved or had Major General Hindmarsh not been a participant in leavening and professionalising the armed forces of a country like UAE," Dr Blaxland said.

Australians are not believed to be directly involved in the bombings, but late last year an Australian commander was reportedly among 14 foreign mercenaries killed fighting against rebels in South East Yemen.

Defence sources have told the ABC having Australians working for Middle Eastern militaries also has a valuable strategic benefit, because the Gulf States are vital allies in the fight against terrorism.

They highlight the fact Australian forces targeting Islamic State operate from the UAE.