The Australian High Court affirmed the conviction of a man earlier sent to jail for authoring an e-book self-help manual that details steps on alleged terror activities such as bomb making and assassination.

In a decision made public on Friday, the High Court upheld the 2008 decision handed down by the New South Wales Supreme Court, which determined that Belai Khazaal had intended to aid terror acts when he published online the manual titled 'Provisions on the Laws of Jihad'.

According to ABC, the more than 100 pages 'jihad guide' was completed by Mr Khazaal in three days, written in Arabic and provided specific instructions on concocting letter bombs and other forms of inflicting harm or killing a target.

The handbook also contained threats that were directed to military officials and diplomats, which for the NSW court were sufficient reasons to put Mr Khazaal behind bars for 12 years, nine years of them with no chance of parole.

However, in subsequent pleas before the Court of Criminal Appeal, the former Qantas cabin cleaner successfully argued that what he wrote in the online manual did not necessarily mean that he had intended to assist would be terrorists or encourage acts of terrorism.

Mr Khazaal's conviction was overturned forcing government prosecutors to bring the case to the High Court.

In the latest decision, justices unanimously ruled that the defendant failed to counter accusations that the e-book he had published was not designed as a manual that would lead to terror attacks.

"In relation to the argument on the appeal, the court held that the evidence pointed to by the respondent did not suggest a reasonable possibility that the making of the e-book was not intended to facilitate assistance in a terrorist act," the High Court was reported by News Ltd as saying on Friday.

At the same time, the new ruling sided with the first conviction handed down by the NSW court, stating "the court held that no error had been shown in the trial judge's directions."

Effective immediately, Mr Khazaal, who was released on bail July last year, will be sent back to jail to serve out his full sentence.