Australian police arrested on Wednesday an 18-year-old man who had allegedly expressed interest in committing a mass-casualty attack, motivated by right-wing ideology.

Police said they expected to file charges against the unidentified man from Albury, a small town 553 km (344 miles) southwest of Sydney.

"The male we've arrested has an extremely right-wing ideology and is focused on neo-Nazi, white supremacist and anti-Semitic material," Scott Lee, Australian Federal Police assistant commissioner, told reporters in Sydney.

"A couple of days ago, what we observed was an escalation in the tone which went to a support of a mass casualty event, and potentially his involvement in that event," Lee said.

Australia, a staunch U.S. ally, has been on heightened alert against the threat of homegrown radicals after several “lone wolf” attacks in recent years.

A white supremacist gunman from Australia killed 51 Muslim worshippers in New Zealand last year.

Australian intelligence agencies have regularly warned of an increased threat by right-wing-aligned individuals since then.