Five terror suspects who allegedly planned to go by boat to Indonesia to join Isis (Islamic State) in Syria are facing extradition from Cairns to Melbourne.

The five men, including Islamic preacher Musa Cerantonio, have been charged with terror offences after being arrested near Cairns last Tuesday towing a 7m fishing boat en route to Cape York in far North Queensland.

Attorney-General George Brandis says the five men, who are in custody, will face Cairns magistrates court tomorrow when an application will be made to extradite them to Victoria.

The men, aged between 21 and 31, were charged overnight with one count each of making preparations for incursions into foreign countries to engage in hostile activities. If found guilty, they face a maximum penalty of life in jail.

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Brandis confirmed that each of the men had had their passports cancelled several months ago by Foreign Minister Julie Bishop.

"These people had been under surveillance for quite some time - that's the reason their passports were cancelled because they had been under surveillance and their intentions to travel to the Middle East to engage in terrorist war fighting were known to the authorities," he told reporters today.

"When it became clear to them that they wouldn't be able to leave the country in an orthodox way, they remained under surveillance so that if they attempted to leave the country in this very unusual way they would be able to be stopped and they were."

Brandis said police had executed 10 search warrants in Melbourne and far north Queensland as part of their investigations.

He stressed that there was no current or impending threat of a terrorist act in Australia and the alert level remained at "probable", where it has been since September 2014.

However, a number of people remain under police surveillance and will be arrested if they attempt a terrorist crime or try to leave Australia to take part in terrorist attacks overseas, Brandis added.

"Obviously, at one level, there was an unusual character to the plot. I know it has been ridiculed," he said.

"But these are serious crimes because they involve preparation to engage in terrorist war fighting overseas, and that is against Australian law."

- AAP