The independence activists claim they were duped by authorities after arriving by speed boat in Australian territory seeking asylum.

Believed to be a family including a woman and 10-year-old child, the group arrived Boigu Island in the Torres Strait on Tuesday. They were detained there before being transferred to Saibai Island and then Horne Island.

On Thursday night, the group – who had gone into hiding in fear for their lives after taking part in the West Papua Freedom Flotilla – say they were told they would be taken to mainland Australia.

“When we are on the aircraft, when the door is closed and the seatbelt is tied, the guy from the immigration tell us we are not going to the mainland but we are returning to Papua New Guinea,” group member Jacob Mandabayan told ABC TV.

A statement from the Freedom Flotilla, a group purporting to represent these asylum seekers, said requests for legal representation were denied on Horne Island and mobile phones and identity documents were confiscated.

There are reports the family fled their home after being hounded by Indonesian authorities for participating in a welcome ceremony for West Papuan independence activists.

Yacob Mechrian Mandabayan, one of the men on board the boat, told Guardian Australia last week he feared for his life after receiving threats from the Indonesian military and police.

“We’ve become refugees in our own country and we ask your help to expose our situation here,” he said. “We need your help. Please.”

Inquiries to the Immigration Department were referred to the office of Immigration Minister Scott Morrison, who is currently visiting PNG and had not answered AAP’s questions on the matter.