Five men are in federal police custody over a bizarre plan to reportedly use a tinnie to get from Cairns to Indonesia before travelling on to join Islamic State in Syria.

News Corp Australia reports the men hauled the tinnie from Melbourne to Cairns and the journey took a long time because of the weight of the boat and the age of their car.

An AFP spokesman confirmed the men had been arrested but did not confirm details surrounding the case.

He said the men were currently helping police with their inquires but the arrests were not related to any impending threat to the community.