Australian police arrested a boy after he was questioned about his social media posts on Tuesday outside the same high school attended by a teenager who last week shot dead a police worker in an attack authorities say was "linked to terrorism".

The boy was arrested when he threatened and intimidated police who wanted to talk to him about his social media activity, New South Wales state police said in a statement.

On Friday, a 15-year-old boy of Iraqi-Kurdish descent identified as Farhad Khalil Mohammad Jabar gunned down a police employee leaving the headquarters of the New South Wales Police. He was shot and killed by police at the scene.

Police provided few additional details about the arrest, but the Australian Broadcasting Corp reported the youth had allegedly praised Farhad on Facebook and posted comments saying police should "burn in hell".

Australia is grappling with a rise in violence perpetrated by radicalized Muslim youths at home while trying to stop others from traveling to Syria to fight with Islamic extremists.

A staunch ally of the United States and its battle against Islamic militants in Iraq and Syria, Australia has been on heightened alert for attacks by home-grown radicals since last year.

Authorities estimate at least 70 Australians have joined militant forces in the Middle East with another 100 or more Australian-based facilitators and supporters.