Sydney Police arrested a teenager in a counter-terror operation

Police in Sydney have arrested a 15-year-old and a 20-year-old in a counter-terror operation.

They have been charged with “conspiracy to conduct an act in preparation for a terrorist act”, Federal Police said.

The arrests are linked to a plot outlined in material seized last year as part of Operation Appleby.

That operation, in September 2014, was sparked by intelligence reports that Islamist extremists were planning random killings in Australia.

Former Prime Minister Tony Abbott said at the time a senior Australian Islamic State militant had called for “demonstration killings”, reportedly including a public beheading.

Another three people, aged between 21 and 22, were also charged for the same offence on Thursday afternoon.

All face potential life sentences if convicted.

At least 800 heavily armed officers arrested 16 people as part of Operation Appleby in September 2014, in what was Australia’s biggest ever anti-terror operation.

Police said the arrests on Thursday were not linked to a new plot, but to documents seized during those raids that talked about a plan to target government and police buildings.

“As a result of putting all of that information together, working through those documents, putting physical and electronic surveillance together, we were able to build a case of conspiracy for five people involved in the preparation of these documents,” said Deputy Commissioner of National Security Michael Phelan.

Those arrested on Thursday are also known to those involved in the terror-linked shooting of Sydney police worker Curtis Cheng, police said.

Mr Cheng, 58, was shot dead outside his police headquarters office as he left work last October.

Police shot dead his attacker, 15-year-old Farhad Jabar, at the scene.

New South Wales Police said the 15-year-old boy arrested on Thursday was charged based on activity when he was 14.

They added that he had clearly been radicalised, although they did not yet know how it had happened.

“It is disturbing that we continue to deal with teenaged children in this environment,” said Deputy Commissioner Catherine Burn.

“To be putting a 15-year-old before the courts on very serious charges that carry a maximum penalty of life imprisonment demonstrates the difficulties law enforcement face.”

Police said a total of 11 people had now been charged under Operation Appleby.