Huge counterterrorism raids in Sydney on Thursday were sparked by security intelligence that the Islamic State movement was planning a random, violent attack in Australia as a demonstration of its reach, the prime minister said.

Australian police detained 15 people and raided more than a dozen properties across Sydney in the largest counterterrorism operation in the country’s history, saying intelligence indicated an attack was being planned on Australian soil.

Prime Minister Tony Abbott said he had been briefed on Wednesday night about the operation that was prompted by information that an Islamic State (IS) organization leader in the Middle East was calling on Australian supporters to kill.

Abbott was asked about reports that the people detained were planning to publicly behead a random person in Sydney.

“That's the intelligence we received,” he told reporters. “The exhortations – quite direct exhortations – were coming from an Australian who is apparently quite senior in [IS] to networks of support back in Australia to conduct demonstration killings here in this country.”

“This is not just suspicion, this is intent and that's why the police and security agencies decided to act in the way they have,” he added.

160 Australians fighting in Middle East

A court official and police told Reuters a Sydney man identified as Omarjan Azari, 22, had appeared in court after the raids and been charged with conspiracy to commit a terrorist act and would remain in custody until a hearing in November.

Prosecutor Michael Allnutt told the court in Sydney that an attack was being planned that “was clearly designed to shock and horrify, perhaps terrify” the community, the Sydney Morning Herald reported.

Azari’s lawyer, Steven Boland, did not apply for bail. Boland was not immediately available for comment

Police said the raids were focused in western Sydney and the Queensland state capital, Brisbane. Around half of Australia’s population of roughly 500,000 Muslims lives in Sydney, with the majority in the western suburbs where the raids occurred.

New South Wales Police Commissioner Andrew Scipione said he had ordered an increased police presence onto the streets after the raids to prevent “troublemakers” taking advantage of heightened tensions.

Up to 160 Australians have either been involved in the fighting in the Middle East or actively supporting it, officials said. At least 20 are believed to have returned to Australia and pose a national security risk, the head of Australia’s spy agency said when raising the threat level last week.

Highlighting the risk of homegrown militants returning from the Middle East, Abbott pledged on Sunday to send a 600-strong force as well as strike aircraft to join a US-led coalition fighting IS militants in Iraq.

Australia had been at the “medium” alert level since a four-tier system was introduced in 2003. A “high” alert level is used when officials believe an attack is likely, while a “severe” level means they believe an attack is imminent or has occurred.

FRANCE 24