Unity Resources Group, the Australian private military firm that handles security for the Australian embassy in Baghdad as part of a $9 million contract, is one of only two military contractors to have killed an Australian in Iraq.

It is also facing a civil suit in Washington DC courts over another shooting and has come to the attention of a United Nations working group over both incidents.

The firm, which the ABC has revealed is fulfilling the embassy security contract with around 60 Chilean military veterans, was involved in the shooting of 72-year-old Australian Kays Juma.

Professor Juma was shot in March 2006 as he approached an intersection being blockaded for a convoy URG was protecting.

Professor Juma, a 25-year resident of Baghdad who drove through the city every day, allegedly sped up his vehicle as he approached the guards and did not heed warnings to stop, including hand signals, flares, warning shots into the body of his car and floodlights. The incident occurred at 10am.

Also in 2006, URG was involved in another shooting incident. This time two Armenian women, Genevia Antranick and Mary Awanis, were killed when their car came too close to a protected convoy.

The family of Genevia Antranick was offered no compensation and has begun court proceedings against URG in the United States.

If successful, the lawsuit would be the first in history to hold private military contractors responsible for actions committed in the theatre of conflict using the legal system back in the Western countries where they conduct business and keep their assets.

American lawyer Paul Wolf took the Antranick case pro-bono and has filed a claim in Washington DC courts. He says the hardest part has been finding the right jurisdiction to file a case against URG.

Having been founded in Sydney in 2000 the company has since been relocated overseas.

"We don't really know where they are, to tell you the truth," Mr Wolf said.

"They are incorporated in Singapore, I don't know why, and they claim that their corporate headquarters is in Dubai in the United Arab Emirates, and have given two different addresses for that - one a post office box in Dubai and another a hotel room in Dubai."

Mr Wolf located an office for Unity Resources Group in the US, only to find that the people on site simply forwarded on any mail they received for the company to another address.

"Unity denies having an office in the US and hasn't admitted it even has an office in Australia. I'm not sure if they're trying to avoid lawsuits or just trying to hide from the public," Mr Wolf said.

But ABC investigations show URG has a significant presence in Australia, a two-storey harbour-front office in Sydney.

The company registered the Millers Point address as a headquarters with the Australian Securities and Investments Commission in January and the premises is full of staff, including one of three company directors, Evangelos Koutavakis.

In the 10 years since it was founded, URG has changed its registered Australian place of business eight times, including locations inside the Sydney Museum of Contemporary Art building and at the offices of a business called Opulence Accountants and Advisors.

URG's operations have not escaped the interest of international agencies; on July 14, 2008 the United Nations Working Group on the Use of Mercenaries corresponded with the Australian Government over some of the company's actions.

The chairman of the working group, Jose Gomez Del Prado, asked the Government whether it knew the nationalities of the men who shot Mary Awanis and Genevia Antranick, as well as whether the Government had conducted any investigations into the killing of Kays Juma.

Mr Del Prado told the ABC that after over two years, "the working group has not received a reply from the Government of Australia".

These incidents, now three years old, continue to dog the company, which has received plaudits from within the Australian Defence Force for its high standards and professionalism.

A senior Australian Army officer speaking to the ABC said of these outstanding controversies, "if this happened in the context of World War II", when it was common practice to destroy entire cities filled with civilians, "this wouldn't even make the news".

"Australians have no idea how lucky they are. They don't have to live with the threat of death from a random source," he said.

"They don't have to live with that, then they throw rocks at people who are taking action to protect lives."

Unity Resources Group did not immediately respond to questions about its Chilean staff or its operations in Iraq.

A DFAT spokesman says the ADF Security Detachment works closely with contracted security personnel to ensure the security of the embassy and safety of Australian diplomats.

"The transition from an ADF-led security operation towards more standard DFAT-controlled, commercial security arrangements reflects the improving security situation in Iraq and both countries' intent to normalise bilateral relations," the spokesman said.

"Every stage of this transition has been based on a careful military risk assessment of the security environment, and the ADF will continue to mentor and supervise contracted security personnel during the transition."