Sydney men Omar Al-Kutobi and Mohammad Kiad have been sentenced to 20 years' jail for preparing to commit a terrorist attack.

Key points: Omar Al-Kutobi and Mohammad Kiad plotted deadly terrorist attacks in Sydney

Omar Al-Kutobi and Mohammad Kiad plotted deadly terrorist attacks in Sydney The duo will spend at least 15 years behind bars

The duo will spend at least 15 years behind bars They were arrested in February 2015 after a tip-off

Al-Kutobi, 25, and Kiad, 27, intended to target a Shiite prayer hall in February last year, but that plan was abandoned in favour of a plot to attack someone with either a knife or machete.

They will both spend a minimum of 15 years behind bars.

In sentencing, Supreme Court Judge Peter Garling said there was enough evidence to suggest the men were on the cusp of carrying out the attack.

"From the seized material and as a consequence of other information received by the authorities during the investigation, a comprehensive chronology of events charting the offenders' radicalisation and the formation of their conspiracy to commit a terrorist act, or acts, can be set out," he said.

"Although neither of the offenders were raised to follow any extreme views related to Islam, it is clear that during and certainly by the end of 2014, both of the offenders had been drawn to and had embraced the ideology of the Islamic State and extremist Islamic views."

Police pounced after tip-off

Al-Kutobi and Kiad had been under surveillance for about a month when they were arrested and charged with preparing to carry out a terrorist attack in February 2015.

Their first target was a Shiite Prayer Hall in Granville where the pair went on February 8 to attack with a petrol bomb, according to Al-Kutobi's testimony during the trial.

But they pulled out after discovering someone was at the hall at the time.

Two days later Al-Kutobi bought a hunting knife and the pair took photos and videos in front of a homemade Islamic State flag.

Court documents revealed an informant tipped off the Joint Counter-Terrorism Team (JCCT) to the plot on February 10.

Counter-terrorism police swarmed the granny flat Al-Kutobi and Kiad shared in Fairfield and arrested the men.

The pair ware taken into custody just minutes after they had filmed the video in which Al-Kutobi could be seen speaking Arabic in front of a home made Islamic State flag.

Police found a number of items including a hunting knife, a machete which had holed drilled into it, the homemade IS flag, two handwritten notes pledging allegiance to Isis and a balaclava.

"Other items located at the offenders premises were intrinsically of such a nature that they provided evidence of the offenders radical beliefs, extremist ideology and alignment with Islamic State," Justice Garling said.

The men pleaded guilty.

Mohammad Kiad (left) and Omar Al-Kutobi were accused of plotting a terrorist attack. ( Supplied: Facebook )

Al-Kutobi previously testified they were never going to carry out the attack and that any conspiracy ended after the failed prayer hall bombing.

But Justice Garling rejected this evidence as having an "air of unreliability".

"It can be accepted they had not undertaken any criminal activity by way of killing or harming any individual at that time, however I am satisfied beyond reasonable doubt that they were in the throes of preparation for such an event," Justice Garling said.

"The offenders were preparing or planning to kill or cause serious physical harm to an unidentified individual. The offenders intended to use either the hunting knife or the machete or both to achieve their object.

"The attack would've occurred within a few hours had it not been for the offenders arrest."

Extremist views must be 'strongly deprecated'

Justice Garling also reached out to Australia's Muslim community, telling the court Australia prides itself on its "pluralism" and "multiculturalism".

"Australia's status as an advanced, peaceful and culturally rich democracy owes much to the contributions of people of diverse faiths, cultures and racial and ethnic backgrounds," he said.

"It is in this context that extremist beliefs and ideologies which preach intolerance, hatefulness and violence towards other members or sections of the Australian community are to be most strongly deprecated.

"Such beliefs and ideologies run utterly counter to what this country stands for. The extremist views held by the offenders in this case which cast non-Muslims as an enemy that need to be destroyed simply cannot be tolerated."

Justice Garling said the beliefs of the offenders were not representative of those held by other Muslims living in Autralia.

Outside court, Detective Chief Inspector Darren Sly applauded the sentence.