Australia's national terror alert level was raised in 2014 amid concerns over attacks by individuals inspired by organisations like IS.
Sydney: Three men will be charged with committing terrorism over alleged "Islamic State-inspired" arson attacks on a Melbourne mosque in 2016, Australian police said on Sunday.
Two men aged 25 and 27 – already in custody over allegedly planning a terror attack on or around Christmas Day in 2016 – will be charged over the fires at the Imam Ali Islamic Centre in November and December.
The third man, aged 29, was arrested on Saturday and will face the same charge of engaging in a terrorist act, which carries a maximum sentence of life imprisonment, for the December arson attack.
"We're not saying that these were just arson attacks, we're going to alleged that these were Islamic State-inspired attacks," Australian Federal Police Assistant Commissioner Ian McCartney told reporters in Melbourne.
"They were designed to influence and put fear into a particularly group in the community."
Assistant Commissioner Ross Guenther, the chief of Victoria state police's counter-terrorism command, said investigators believed the centre, which doubles as a place of worship, was targeted as it was Shia.
"This centre is a Shia centre, so what will be alleged is that those that committed this attack adhere to an extremist Sunni ideology that leads up to the conclusion and the link that it is part of an ISIS-influenced or inspired attack," he said.
Islamic State, also called IS or ISIS, is a Sunni extremist group that oftens targets Shia Muslims.
Australia's national terror alert level was raised in September 2014 amid concerns over attacks by individuals inspired by organisations such as IS.
Authorities say 13 attacks have been prevented in the past few years.
The latest thwarted attack allegedly involved IS-directed plans to build a bomb destined for an international flight out of Sydney, with a second poisonous gas plot also in the works.
Several terror attacks have taken place in recent years, including a Sydney cafe siege in 2014 which saw two hostages killed.