Australian police have detained a 23-year-old man and expect to charge him under counter-terrorism laws, after raids on about a dozen homes yielded an unspecified number of weapons.
The raids were conducted by state and national police on 11 homes in Melbourne yesterday.
Computer equipment, including a memory stick containing violent material, was seized, along with a number of registered firearms and fake weapons, police said.
Police said they expected to charge the man with "collecting or making documents likely to facilitate terrorist acts", an offence under Australia's criminal code. The maximum sentence for the charge is 15 years in jail.
"I would like to reassure people that we have not identified any immediate threats that pose immediate concerns to the safety of the community," Victoria Police Assistant Commissioner Steve Fontana said in a statement.
Australia, a staunch US ally, has gradually tightened its national security laws since the September 11, 2001, airliner attacks on the United States. Under those security laws, police can detain a person for up to seven days for questioning.
The Australian Federal Police declined to comment on the man's ethnic or religious background. The Islamic Council of Victoria said the police had briefed members of the Muslim community about the raids.
"The last thing we want is any kind of terrorist attack anywhere in the world, let alone in Australia, and it's very reassuring that the authorities are being very vigilant in keeping our community safe," Sherene Hassan of the Islamic Council of Victoria told Australian Broadcasting Corporation radio.
Australia has never suffered a major peace-time attack on home soil, although 88 Australians were killed in the 2002 nightclub bombings of the Indonesian resort island of Bali and Australia's embassy in Jakarta was bombed in 2004.
Australian authorities have disrupted four major plots since 2000, with 23 people convicted of terrorism offences.