One man has been charged and police expect to charge two others with committing an "Islamic State-inspired" terrorist act following an investigation into arson attacks on a Shia Islamic centre in late 2016.

A 29-year-old man from Meadow Heights, in Melbourne's north, was arrested late on Saturday night by officers from the special operations group in connection with a fire in December last year.

He was charged and remanded in custody early on Sunday morning.

It will be alleged that the Meadow Heights man and two others, who are currently in custody and awaiting trial for allegedly planning a terrorist act on Christmas day in 2016, caused two serious fires at the Imam Ali Islamic Centre at Fawkner, in November and December of 2016.

Police said it would be alleged that those who committed the attack were members of an "extremist Sunni ideology".

"In terms of the charges being laid, we're not saying these are just arson attacks," said Assistant Commissioner Ian McCartney of the Australian Federal Police.

"What we're going to allege is that these were Islamic State-inspired attacks. They were inspired and designed to influence, put fear into a particular group in the community.

"These are significant and serious charges and carry a maximum penalty of life in prison."

Assistant Commissioner McCartney said there was a "strong influence" behind the attacks from Islamic State.

There were two fires at the Imam Ali Islamic Centre late last year. ( ABC News: Iskandar Razak )

No threat to community

Victoria Police Assistant Commissioner Ross Guenther said the three men were connected to an alleged plot in December 2016.

"The matters that they're in custody for are those matters we allege involve a plot to execute a terrorist action in Melbourne around the Christmas [2016] period," he said.

"These acts are quite a different matter because we're saying these were committed.

"So they're not acts in preparation [of a terrorist act]. We're saying this was an act of terrorism and has been completed."

Assistant Commissioner Guenther said the impact of the attacks on the Shia Muslim community were significant.

"It interferes with the whole process of social cohesion that we so heavily promote," he said.

"So I think if you look back at the methodology behind ISIS, it's really about separating, it's about being divisive. That's very much what this was intended to be."

Assistant Commissioner Guenther said they were not aware of any other threat to that community at the moment.

"With the advent of the attacks in Spain I'm very conscious of the anxiety that's in the broader community," he said.

"I would like to remind everyone that you will see over this weekend an increase in [police] patrols and it might take a bit longer to get into some of the sporting events.

"It's just important to realise that we don't stand back on these things and we leverage off world events and as a result there will be some additional frontline police at public events this weekend."