Australian police charged a man with terrorism offenses Thursday following raids in which they seized firearms, computer equipment and a USB stick containing what they said were "violent extremist materials."

Officers swooped onto properties in six Melbourne suburbs Wednesday in a simultaneous raid, the Australian Federal Police and Victoria state police said in a joint statement. The 23-year-old, whose name was not released, was charged with four counts of collecting or making documents likely to facilitate terrorist acts. If convicted, he could face a maximum sentence of 15 years in prison.

Among the police targets was the Al-Furqan Islamic Information Centre, which hosts an Islamic book store and library and offers youth activities, daily prayers and classes. The center's representatives did not respond to calls and emails Thursday, though a spokesman on Wednesday confirmed that police spent about 12 hours inside and took several items.

Steve Fontana, Victoria police assistant commissioner for crime, said police had identified no immediate threats to public safety.

"We will continue to work to ensure that all steps are taken to protect all members of the community," he said.

Terrorism expert Greg Barton, director of Monash University's Centre for Islam and the Modern World, said the Al-Furqan center represents the "fringe of the fringe."

"Their talk is extreme on their website — they've got a link to an interview with Anwar al-Awlaki, the former Yemeni-American leader to al-Qaida," he said. "So there's no question they're flying their colors in a fairly flagrant fashion."

Still, the group only attracts a few dozen regular members, has no broad influence and had garnered little attention until Wednesday's raids, Barton said.

"They'd ordinarily be a group that's all talk and no action except for the possibility somebody might take on board their ideas and move on and go abroad," Barton said. "It's got stepping stone potential, I think, which is why the authorities were watching them."

Over the past few weeks, the group made several postings on its Facebook page and website referencing a "spy" that had been uncovered in their community. It was not clear from the postings what specifically the group was referring to.

Barton said he suspects that once the group began posting publicly about being under surveillance, authorities decided to move in.

Police declined to comment on the spying allegations or if other suspects were being investigated.