THE brother of hard-line WA Islamic preacher Junaid Thorne is one of five men arrested by Federal Police over an alleged plan to pilot a boat to Indonesia and join ISIS.

According to The Courier Mail, Shayden Thorne and Musa Cerantonio are among those who were arrested in Cairns, in north Queensland.

Shayden Thorne is the brother of former Perth man self-styled Islamic preacher Junaid Thorne, whose rantings have attracted support from Australian high school teens and university students, many of them in Brisbane.

In 2011 Shayden Thorne was arrested in Saudi Arabia for alleged terrorism offences and deported to Australia in 2014.

Camera Icon Shayden Thorne’s mother holds a photograph of her son, when he was being held in a Saudi Arabian jail in 2011. Credit: News Limited

Cerantonio, 30, has had his passport cancelled and tried to carry out his jihadi dream by getting to Indonesia in a tinnie.

He has been previously arrested in the Philippines for his radical views and has been described as an “inspiration’’ to terrorists worldwide for his preachings.

The Courier-Mail reports five men hitched a seven-metre runabout to a clapped-out car for a road trip from Melbourne to Cairns, the first leg in a bid to sail to Indonesia then join ISIS terrorists in Syria, it is alleged.

The five men were arrested in Cairns on Tuesday and questioned by Australian Federal Police.

The bizarre plot involved the men launching their 7-metre boat in far north Queensland to get to Indonesia, police say.

It’s believed the AFP decided to swoop because they feared the men would come to harm at sea.

Australian Federal Police assistant commissioner Neil Gaughan confirmed on Wednesday the men had been under investigation for “a number of weeks”.

The men, aged between 21 and 33, have not been charged with any offence.

Shayden Thorne was arrested in Saudi Arabia in 2011 for terrorism offences and deported to Australia in 2014.

“I must stress that the investigation remains active and the focus is on ensuring community ... safety and disrupting criminal activity either on Australian soil or by Australians attempting to join overseas conflicts,” Mr Gaughan said.

Authorities are investigating whether the men were planing to make their way through Indonesia to the Philippines, with a plan to end up in Syria.

Victoria Police deputy commissioner Shane Patton said there was no threat of a terrorism incident arising from the investigation.

Still, he said the alleged plot should not be downplayed.

“This is a serious attempt by five men who have had their passports cancelled in attempting to exit Australia ... ultimately we’re investigating the intention to possibly end up in Syria to fight,” he said.

The men five men were described by authorities as “associates” but police would not say if they attended the same mosque.

Deputy Commissioner Patton said authorities were “continually monitoring persons of interest”.

“We will continue to disrupt, if they’re trying to get this, be it via boat, via plane or any other method. We have an obligation to ensure that people can’t go and support terrorism or fight in other conflict zones,” he said.

He said he would not divulge where the men were being held for security reasons.

Deputy Commissioner Patton also confirmed eight warrants were executed on Tuesday in Melbourne and one in Queensland in relation to the alleged plot.