The 1902 execution of Australian soldier and bush poet Harry 'The Breaker' Morant during the Boer War has been taken up by the Federal Government, which believes his trial may have been unfair.

Morant and Peter Handcock were executed for the murder of several Boer prisoners, but always insisted they had only been following "take no prisoners" orders issued by their British commanders.

A third Australian, George Whitton, was convicted but escaped execution and was released after authorities considered a petition signed by 80,000 Australians and lobbying by a young British MP, Winston Churchill.

Now Attorney-General Robert McClelland says he will take up the case with the British government, citing "procedural fairness concerns".

Mr McClelland has written to James Unkles, a lawyer who for several years has researched the Morant case, telling him that he has told his department to prepare a submission for the British authorities.

Mr Unkles told ABC News Online Mr McClelland "is as committed to the case as I am".

Mr Unkles petitioned the Queen two years ago for a posthumous pardon - but the move was rejected late last year by the then-British defence secretary Liam Fox.

"Until now I have been running the case myself, but now I have the support of the Australian Government. The letter has altered the whole political landscape," Mr Unkles said.

"They were not tried according to law. I've found compelling evidence the orders [to take no prisoners] were made by the British and they have never been held to account.

"There was a lack of due process. They were not even allowed to appeal the sentence and were given only a few hours notice before they were shot."

In his letter, Mr McClelland says, "I have been persuaded ... that this case does raise procedural fairness concerns".

"I want to ensure that the British Government is aware that questions exist as to whether the men received fair treatment in accordance with the standards accepted at that time," Mr McClelland wrote.

Sorry, this video has expired Author welcomes appeal for Morant review ( Ros Childs )

Larrikin bushman Morant was married for a short time to legendary anthropologist Daisy Bates, who reportedly threw him out after he failed to pay for the wedding and then stole some pigs and a saddle.

He wrote verse for The Bulletin magazine and became friendly with Henry Lawson and 'Banjo' Patterson - who later wrote of the guilt suffered by the man who defended Morant at the trial, Major JF Thomas from Tenterfield, NSW.

Patterson, writing in a newspaper years later, recounted a conversation he had with Major Thomas.

"I never believed the execution would be carried out. When I found that the thing was serious, I pulled every string I could; got permission to write to Australia, and asked for the case to be reopened so that I might put in a proper defence," Patterson quoted Major Thomas as saying.

"It was of no use, Morant had to go. He died game. But I wake up in the night now, feeling that Morant must have believed that he had some authority for what he did and that I ought to have been able to convince the Court of it."

Patterson wrote that Major Thomas carried with him a "bulky bundle" of evidence, papers and cablegrams, for many years "grieving over the matter till it seriously affected his mind".

"He blamed himself, in a measure for the death of Morant but I could not see that he had failed to do the best he could with a very unpleasant business."

Morant's last words, made famous in the 1980 film, were reputedly "Shoot straight you bastards. Don't make a mess of it", but a contemporary account quotes him as demanding his blindfold be taken off then saying "Be sure and make a good job of it!"

Either way, as JF Thomas said, he died game.

No time frame has yet been given for the approach to the British by Mr McClelland.