The Australian Immigration Department has warned a group of Papua New Guineans against crossing Torres Strait as part of a campaign to be given Australian citizenship.
Papua Australia Plaintiff United Affiliates wants Australia to recognise that Papuans were not given a choice to remain as Australians when PNG became independent in 1975.
Its leader Jonathan Baure says 120 people in 12 dinghies have left Daru Island for the 150 km trip to the Australian mainland.
He says another 20 boats are set to leave the island in the coming days.
Australian authorities say the group could face a range of enforcement measures, including interception by Customs and Border Protection, the seizure of their vessels, refusal of entry and removal from Australia.