Australia on Saturday defended its hardline immigration policy after two asylum-seeker deaths, weeks of protests and several medical evacuations from a camp in the tiny Pacific Island nation of Nauru.

Prime Minister Malcolm Turnbull said Australia's policy of refusing to accept asylum seekers who arrived by boat was necessary to deter people smugglers from organizing dangerous sea voyages.

"We do not theorize about border protection," he told reporters as he campaigned ahead of an election on July 2.

"We know what happens when those policies were abandoned: 1,200 people died at sea ... it was a catastrophe."

Asylum seekers intercepted attempting to reach Australia by boat are sent for processing to camps on Manus Island in Papua New Guinea or on the Pacific island state of Nauru. They are not eligible to be resettled in Australia.

Papua New Guinea has said it plans to close the Manus Island detention center after its Supreme Court ruled it unlawful.

Controversies arising from Australia's immigration policy have become a major headache for Turnbull in the buildup to the election.

In the past month two asylum seekers detained on Nauru have set themselves on fire and one of them, an Iranian, died. Another asylum seeker died of a heart attack last week.

On Friday a woman was flown from the island to the Australian city of Brisbane in a critical condition after a cesarean operation.

Immigration Minister Peter Dutton on Saturday defended her treatment, saying medical assistance provided on Nauru was "significant" and she was "receiving the medical attention that's required," according to Australian Associated Press.

State-owned broadcaster SBS reported that the woman was a 22-year-old Somali named Naima Ahmed, and that her condition was no longer life-threatening.

Refugee advocate Ian Rintoul, a spokesman for the Refugee Action Coalition advocacy group, told Reuters by phone that the government was "defending the indefensible".

"The deterrence policy is what's wrong, there are plenty of ways for people to get safely from Indonesia to Australia if the government is of that mind," he said.

He said that refugees on Nauru were "getting increasingly angry and holding demonstrations every day."