The five have been held in immigration detention before being sentenced to between two and three years in prison for immigration violations.

After a successful appeal to Jayapura High Court, they were told they were free, but euphoria lasted only a few days. Prosecutors, under instruction from the Attorney-General in Jakarta, launched an appeal to the Supreme Court to get the guilty verdicts reinstated. Those appeals were rejected yesterday.

"There are two dossiers. The one on [pilot] William Henry Scott Bloxam, the decision is 'appeal rejected'," said Justice Ali Hatta, the Supreme Court's spokesman. "The other one is under the name of Vera Bloxam and her other friends. The decision is 'No' … which means 'cannot' be accepted'."

Asked if this meant the five were free to leave, Justice Hatta said: "Yes, the decision made by the Supreme Court upholds the Jayapura High Court."

Members of the Merauke Five declined to comment yesterday, saying they wanted to hear the decision officially.

Mr Scott-Bloxam informed Indonesian authorities of their lack of visas and security clearances while en route to Merauke, but was told to land anyway. The Australians were assured everything would be OK and they could return to Horn Island as planned after three days if they paid a fine.

The relentless and extraordinary prosecution of the case was driven by the Attorney-General, Hendraman Supandji, according to lead prosecutor Yafeth Bonai. The case was linked by the Indonesians to the Australian practice of burning illegal Indonesian fishing vessels.