Police have charged a 20-year-old man they allege was planning a "mass casualty" terror attack targeting public buildings in Western Australia.
Jayson Joseph Michaels, 20, from the town of Bindoon north of Perth, appeared in the Perth Magistrates Court on Friday, facing five charges.
Premier Roger Cook told a press conference on Friday it would be alleged Mr Michaels was plotting to attack WA Parliament House, police headquarters and Muslim faith places of worship.
WA's Joint Counter Terrorism Team — made up of WA Police, the Australian Federal Police and ASIO — confirmed they had been investigating Mr Michaels' online activities.
They said that led them to execute a search warrant at his home in Bindoon yesterday.
Mr Michaels has been charged with acting in preparation for a terrorist act, using a carriage service to menace or harass, possessing a prohibited weapon and two firearms offences.
It's alleged Mr Michaels was motivated by a white supremacist ideology, Mr Cook told media on Friday afternoon.
"There is no ongoing threat," he said.
WA Police Commissioner Col Blanch said police had been monitoring Mr Michaels since January.
"We have now seized firearms, imitation firearms, a ballistic vest, gas masks, lock picking equipment," he said.
"Most concerningly, there was a notebook that outlined preparations for a terrorist attack at significant locations including the WA police headquarters building, Parliament House, and places of Muslim faith in WA," Mr Blanch said it would be alleged.
Commissioner Blanch said police would allege he was acting alone, adding the charge was "extremely serious" and has a maximum penalty of life imprisonment.
He said seven firearms had been seized and a large knife collection.
Commissioner Blanch said the man lived with his parents and alleged he had been radicalised online.
Security had been bolstered at Muslim places of worship and Parliament House, the commissioner said.
Australian Federal Police Superintendent Peter Hatch said it was the first time a person had been charged with preparing for a terrorist act in WA.