Four Melbourne men have been jailed for plotting to sail to the Philippines to encourage Muslim militants to overthrow the government and introduce sharia law.

Key points: The Melbourne men bought a four-wheel drive, which they used to tow their boat to Cape York

The Melbourne men bought a four-wheel drive, which they used to tow their boat to Cape York They planned to join efforts to overthrow the government in the southern Philippines

They planned to join efforts to overthrow the government in the southern Philippines Two of the men were brothers, and their father provided $90,000 to fund the plan

The men bought a boat in May 2016 and planned to sail from Cape York, in far north Queensland, to the southern Philippines, in order to work with Muslim militants to overthrow the government.

Paul Dacre, Antonino Granata and Kadir Kaya have each been sentenced to four years in prison, with a non-parole period of three years.

Murat Kaya was sentenced to a jail sentence of three years and eight months, with a non-parole period of two years and nine months.

"The accused [men] agreed to acquire a boat to leave Australia in a covert manner to facilitate entry to The Philippines," Justice Michael Croucher said.

"The whole venture was poorly planned and doomed to fail."

In sentencing the four men, Justice Croucher told the court he had considered how they had behaved in prison, and that they had good prospects for rehabilitation.

"It seems they accept they have done wrong and they accept the authority of this court."

Co-offenders Shayden Thorne and Robert Cerantonio, who have also pleaded guilty, are yet to be sentenced.

'An affinity with Islamic extremism'

Five of the offenders had already pleaded guilty when Thorne entered a guilty plea in the Supreme Court in Melbourne today.

That led to the lifting of suppression orders that had been in place preventing reporting of the case.

Documents lodged by prosecutors said the six men "agreed to encourage acts [directed to] overthrow by force or violence the government of the southern Philippines".

The group spoke in code, adopted aliases and sought bank loans to fund a "foreign incursion", documents filed with the Supreme Court revealed.

Murat Kaya is one of six Melbourne men who have pleaded guilty. ( AAP: Tracey Nearmy )

The prosecution said each of the men "had an affinity with Islamic extremism", particularly Cerantonio, who had spent a year living in the Philippines and was said to be the group's "leader and religious adviser".

Court documents said he supported Islamic State hostilities in Iraq and Syria and advocated for sharia law.

"Each offender can be linked to evidence consistent with support for the aims and ideals of Islamic extremism and jihad as well as antipathy to Australian society and the rule of law," the prosecution said in its submission.

While the prosecution did not detail how the men planned to enact their plan to overthrow the government, it said that the plot was "not a misconceived or fanciful notion".

"The encouragement of the overthrow of a foreign government by force or violence endangers the fabric of that society," the Crown argued in submissions to the court.

Haci Kaya, the father of Murat and Kadir Kaya, supplied the group with $90,000 to fund their plan, the documents reveal.

The men had purchased a four-wheel drive and used it to tow their boat to Cape York.

They had also bought survival gear and navigational equipment, and had drawn maps of the seas on their route.