A member of Australia's Special Air Service (SAS) regiment claims he was subjected to a brutal sexual assault as part of a secretive training program with the elite unit a decade ago.

Evan Donaldson has come to Canberra to speak with federal politicians about his ordeal and frustrations with the military bureaucracy.

In 2006, he said he was put through secret SAS "conduct after capture" training in which he endured horrific injuries.

Trooper Donaldson detailed an incident while he was blindfolded, handcuffed and wearing a thin hospital gown.

When the young recruit asked to go the toilet, an instructor viciously attacked him.

"I remember partially tripping in one instance because I couldn't see where I was going. Of course they have to escort you and one of the guards assaulted me with his knee to my buttocks, which resulted in a tear and bleeding," Trooper Donaldson told ABC News.

Sorry, this video has expired Trooper Evan Donaldson claims he was assaulted while in the SAS in 2006

He told the ABC he had battled traumatic stress disorder as a result of the incident and because of his dealings with military bureaucracy.

Trooper Donaldson's wife Phoebe, a medical doctor, has accompanied him to Canberra for support.

"I hope that what we've gone through will stop it happening to other people and that the wider public can see what their country is doing to their heroes," she said.

Pay Donaldson's wages and legal bills: Lambie

Independent Senator Jacqui Lambie lashed out at the Army over its treatment of Trooper Donaldson.

She used parliamentary privilege in the Senate to accuse Army top brass of deliberately trying to discredit Trooper Donaldson and end his career in the SAS.

She said senior Army figures illegally tried to change his rank, strip him of wages and spread false information about his career.

"These men have faced death many times in service of their country, they have earned and deserve respect," she said.

"Pay SAS Trooper Donaldson the wages and entitlements the Australian Government has stolen from him and his family, and pay his legal bills."

Senator Lambie urged the Prime Minister to meet with Trooper Donaldson to hear about his ordeal. She said the Army had deliberately deceived a succession of Defence ministers on the matter.

"Trooper Evan Donaldson's grievances have been the subject of six, almost seven years of official government investigations," she said.

Since 2009 six consecutive defence ministers must have been misled by their Department, including the current Defence Minister Marise Payne," she said.

Xenophon: 'Nothing short of a travesty of justice'

Independent senator Nick Xenophon said the alleged incident was unacceptable and cruel and must be resolved as soon as possible.

"What Trooper Donaldson has been subjected to is nothing short of a travesty of justice," Senator Xenophon said.

"What he has gone through has been appalling. Defence needs to sort this out as a matter of urgency".

Trooper Donaldson, a father of one, said his family was seeking compensation because they were crippled with huge debts as a result of years of no wages and legal bills.

The Department of Defence said it could not comment on Trooper Donaldson's case unless he signed a privacy consent form.

However he has refused to do so based on his experience of dealing with the department during the past decade.