Australian Prime Minister Tony Abbott on Wednesday announced an official review into this week's deadly cafe siege in Sydney. Key questions include how the gunman accessed a firearm in a country with strict gun ownership laws, and why security agencies were not watching him.

Abbott said that the gunman had a firearms license, but Australian broadcasters ABC and Sky News later reported that he did not.

A self-styled cleric, Man Haron Monis took 17 people hostage inside the Lindt cafe in central Sydney's Martin Place on Monday morning. The siege ended 16 hours later in gunfire as police rushed in to free those inside. Two hostages were killed - 38-year-old barrister and mother of three Katrina Dawson, and the cafe's 34-year-old manager Tori Johnson - along with Monis.

Abbott told journalists on Wednesday that Iranian-born Monis had been on the Australian Security Intelligence Organisation's watch list in 2008 and 2009, but added the 50-year-old had dropped off the list for unknown reasons. Monis was under watch for sending offensive letters to families of Australian soldiers killed in Afghanistan.

Last Friday, three days before the cafe siege, Australia's highest court had refused to hear Monis' appeal against convictions for sending the letters. The cafe where the siege took place was a short walk from the courtroom where the ruling was delivered.

There were also charges against Monis of being an accessory to the murder of his ex-wife, and another charge earlier this year over the 2002 sexual assault of a woman. He had been out on bail on all charges.

Last month, Monis posted a message in Arabic that pledged allegiance to "the Caliph of the Muslims," which some have interpreted as being the "Islamic State" (IS) militant group. Monis was understood to be upset at Australia's participation in the battle against IS.

Iran said on Wednesday that it had filed a request for Monis to be extradited, but that this did not happen due to the lack of an extradition agreement with Australia. Monis was granted asylum in Australia in 2001.

Search for answers

"We want to know why he wasn't being monitored given his history of violence, his history of mental instability and his history of infatuation with extremism," Abbott said on Wednesday. The prime minister however acknowledged that it was impossible for security agencies to monitor everyone.

"Clearly we can't monitor people all the time, so we have to judge people who are potentially violent," Abbott said on ABC radio, when pressed on the threshold of perceived danger for a suspect to be monitored.

Police Commissioner for the state of New South Wales, Andrew Scipione, said police had asked that Monis not be granted bail, but the court ruled otherwise. He said Monis was not on a national security watch list because the charges against him were not politically motivated.

"Can we, should we, would we? Clearly, we work on a priority-based system so if somebody is on a national security watch list, then we pay particular attention to them. But on this occasion, this particular individual was not," Scipione said.

The inquiry announced by Abbott is expected to report back by the end of January.

Mourning for victims

Thousands of people have been walking through Martin Place, leaving flowers and paying tribute to victims Dawson and Johnson at a makeshift memorial.

"Apparently seeing an opportunity, Tori grabbed the gun," Sydney's Catholic Archbishop Anthony Fisher said at a memorial service on Tuesday, in a reference to reports that Johnson brought the standoff to an end by seizing Monis' firearm.

"Tragically, it went off, killing him. But it triggered the response of police and eventual freedom for the hostages."

Officials have not said whether the victims died in crossfire as police stormed in, or if they were shot by their captor.

jr/sms (AP, AFP)