SYDNEY • Australian police said they believe a 15-year-old boy who killed a police employee in Sydney had links to terrorism.

The boy was identified by Australian media reports as high school student Farhad Khalil Mohammad Jabar. The Sydney Morning Herald said he went to school 300m away from where the attack took place.

Farhad was shot dead by police last Friday after he gunned down Mr Curtis Cheng, 58, at close range outside the state police headquarters. Police said yesterday that the teen was of Iraqi-Kurdish background and had been born in Iran. He had been shouting religious slogans before shooting Mr Cheng, according to witnesses.

"We believe that based on the information we have, this was politically motivated," said Mr Andrew Scipione, police commissioner for the state of New South Wales, of which Sydney is the capital. "If it's politically motivated violence, then under our definition, it is deemed necessarily an act of terrorism."

The incident in Parramatta, in Sydney's west, comes as Australia remains on high alert for attacks, citing threats posed by local supporters of Islamic State in Iraq and Syria (ISIS) militants.

Mr Scipione said early indications were that the boy was acting alone, and police had no warning of any attack. He said they were not sure whether Mr Cheng was targeted simply because he had left the police building. "We may never know that. But he was certainly targeted in terms of the shooting. It was a direct shooting," he said.

"We're a long way from establishing a full picture" of the attacker, Mr Scipione added. "His exact motivation still remains a mystery."

Prime Minister Malcolm Turnbull said in a separate news conference yesterday that governments and police are working together to ensure the country's security.

"This appears to have been an act of politically motivated violence so at this stage it appears to have been an act of terrorism. It is a shocking crime," he said.

"It was a cold-blooded murder, targeting the New South Wales Police Service. It was doubly shocking because it was perpetrated by a 15-year-old boy. And it underlines the importance of families, communities, leaders being very aware of whether young people are becoming radicalised."

Last September, Melbourne police shot dead a "known terror suspect" who stabbed two officers, just a day after ISIS called for Muslims to indiscriminately kill Australians. In December, Iranian-born self-styled cleric Man Haron Monis and two hostages were killed after a 17-hour siege at a central Sydney cafe.

Mr Turnbull urged Australians not to vilify the Muslim community. "We must not vilify or blame the entire Muslim community with the actions of what is, in truth, a very, very small percentage of violent extremist individuals. The Muslim community is our absolutely necessary partner in combating this type of violent extremism."

AGENCE FRANCE-PRESSE, BLOOMBERG, REUTERS