Australian Prime Minister Tony Abbott conceded on Sunday that "the system" had let the nation down by allowing a "monster" to launch a deadly attack on a Sydney cafe.

"Plainly, this monster should not have been in our community. He shouldn't have been allowed into the country. He shouldn't have been out on bail. He shouldn't have been with a gun. And he shouldn't have become radicalized," Abbott said.

Speaking to the press about the initial report investigating the incident, Abbott admitted that authorities had realized fairly quickly that the gunman, self-styled Islamist cleric Man Haron Monis had lied on his first application to come to Australia and had invited scrutiny into his citizenships proceedings multiple times.

The review revealed that in the weeks leading up to the 17-hour siege on a Lindt chocolate cafe in downtown Sydney, which left three, including the gunman, dead, 18 calls were made to authorizes concerning Monis. All of these calls were concerning offensive material on his Facebook page.

"None of the calls related to any intentions or statements regarding a pending attack - imminent or otherwise," the review said, adding that all were all evaluated by intelligence and police authorities.

No wrongdoing by the intelligence community

Abbott said the review found that the decisions made about Monis at various levels -immigration, mental health, security - were justifiable considering the circumstances. Although Monis was free on bail while faces murder charges over the death of his ex-wife, "he fell well outside the threshold to be included in the 400 highest priority counter-terrorism investigations."

"We have some hundreds of people who are currently talking about violence against members of the community. We have many more people who are susceptible to ideologies which justify violence. We can't monitor all of them," Abbott added.

Monis, originally from Iran, arrived in Australia in 1996 on a business visa and swiftly applied for asylum, eventually obtaining citizenship. He was the subject of numerous counter-terrorism discussions between 2008 and 2014.

In 2012, he was convicted of sending hate mail to the families of Australian soldiers who died in Afghanistan.

The report showed the balance between individual freedom and community protection needed to be reassessed, Abbott said. The prime minister is set to give a speech on national security on Monday. He is likely to use the report to call for stricter counter-terrorism and immigration measures.

es/sms (AFP, Reuters)