A pregnant Somalia refugee rape victim was seeking a court order to keep her in Australia before the government flew her to Nauru without providing the abortion she had requested.
The case of the 23-year-old woman, known by the pseudonym Abyan, has amplified criticisms of the government's tough policy of refusing to allow asylum seekers who arrive by boat to settle in Australia under any circumstances.
Asylum seekers who attempt to reach Australian shores are transferred to Australia-run immigration detention camps on the impoverished Pacific island nations of Nauru and Papua New Guinea.
Abyan alleges she became pregnant at a detention camp on Nauru when she was raped in July.
She requested an abortion and the Australian government flew her to Sydney on Sunday last week on a commercial flight from the tiny atoll for the 14-week pregnancy to be terminated.
But she was flown the 2,500 miles back to Nauru on Friday in a chartered private jet, in what some critics suspect was a hastily arranged bid to beat a potential court order allowing her to stay.
Government officials said she was sent back because she had decided to not proceed with the termination. Abyan said in a statement from Nauru she had not changed her mind, but had been denied an interpreter and counselling.
"I have been very sick," she wrote in a signed statement. "I have never said that I did not want a termination."
Abyan's lawyer George Newhouse said he had started preparing an application for a temporary court injunction keeping her in Australia when he discovered she was to be sent back to Nauru. She was gone before he could make the application.
"When we heard an hour before she was being removed from the country without treatment - that that was going to happen - of course we tried to stop her for going back without treatment," Mr Newhouse told Australian Broadcasting Corporation radio, adding it was a temporary injunction and not an effort to keep her in Australia permanently.
Immigration minister Peter Dutton denied Abyan's claims that she was not given access to doctors or an interpreter.
He said 240 asylum seekers who have come to Australia for medical treatment from Nauru had succeeded in getting court injunctions preventing their return.
Neil Skill, first assistant secretary of the Department of Immigration and Border Protection, told a Senate committee that he decided to charter a flight because there were no commercial seats available on the day and he was worried about the disruption that Abyan might cause on a commercial flight if she did not want to return to Nauru.
Abyan could later decide to return for an abortion in Sydney, Skill said. Abortions are legal for the first 20 weeks of pregnancy in Australia.