SYDNEY • Two terrorists who plotted to blow up a prayer hall in Sydney and "cut heads" off civilians in the name of the Islamic State in Iraq and Syria group were both jailed for 20 years yesterday.

Omar Al-Kutobi, 25, and Mohammed Kiad, 27, were arrested last year at a flat they shared, where the police found a hunting knife, a machete, homemade explosives and an ISIS flag. A video had just been made of Al-Kutobi - who was born in Iraq and took Australian citizenship in 2013 - brandishing a knife and making threats, the Supreme Court heard.

Justice Peter Garling said the police also found two notes, one of which said: "We are the soldiers of the Islamic State, we are here to cut your heads."

The pair had, two days earlier, gone to a rival Shi'ite prayer hall in western Sydney, intending to set off a blast.

They were surprised by a man and escaped from a police chase before deciding to focus on attacking random members of the public.

Justice Garling sentenced them to serve no less than 15 years before being allowed parole, noting their planning was substantial and had reached a late stage.

An informant had tipped off the police about their plans and the pair had been under surveillance for weeks. "It is clear that... 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," Justice Garling said.

Kiad - who was born in Kuwait and moved to Australia in 2012 - and Al-Kutobi pleaded guilty to conspiring to plan a terrorist attack.

Australian officials say 11 terror attacks have been prevented on home soil in the past two years. But several have taken place, including the murder of a Sydney police employee last year.

AGENCE FRANCE-PRESSE