Gillian Triggs, the president of the Human Rights Commission, has labelled as “curious” and “extraordinary” the case of a pregnant Somali refugee who was returned to Nauru by the Australian government.

The 23-year-old, known as Abyan, has alleged she became pregnant after being raped on Nauru. She was flown to Australia last week for an abortion but was returned to the island after five days, with the immigration department saying she had changed her mind.

“It’s extraordinary that she was expected to reach a decision in such a short space of time and when the answer wasn’t given immediately she’s literally airlifted back to Nauru,” she told ABC TV’s Lateline.

The immigration department on Monday denied it imposed an arbitrary “abortion deadline”.

A senior official told a Senate estimates hearing the woman declined two medical appointments to discuss the termination.

But in a statement released by her lawyers, Abyan said she did not receive counselling or see a doctor.

“It makes a much broader point that the lack of transparency, the secrecy with which we conduct these detention centres and what goes on in them and of course in our own detention centres in Australia, that is really a core problem and why we really need some form of independent monitoring,” Triggs said.

The woman reportedly still wants to go ahead with the abortion - but not in Australia.

“Yes I still want an abortion. But I don’t want to go to Australia, I want to go to another country,” she was reported as telling The Australian on Tuesday.

She reiterated that she never said no to the procedure, but was “physically and mentally sick and I wanted to make sure I could make my health good first”.