Sydney: A pair of heavily pregnant refugees were refusing to disembark from a bus in the northern Australian city of Darwin for the third day on Monday in protest against attempts to force them into detention for the remainder of their pregnancies.

The women were brought to Australia from the Pacific island nation of Nauru, where Canberra detains asylum seekers to deter them attempting the dangerous boat journey to its territory, often from Indonesia.

Nauru lacks proper medical facilities and the women, who were living freely on Nauru after receiving refugee status, were told that they would be housed in the community, Refugee Action Committee spokesman Ian Rintoul said.

On arriving in Darwin on Saturday, however, they were placed on a bus to be taken to the Wickham Point detention centre, at which point they refused to disembark and enter detention.

The average daily temperature at Darwin Airport in December is 32.6 Celsius (90,68F), according to the Australian Bureau of Meteorology. On Monday, the temperature was over 34C.

Opposition Greens Party Senator Sarah Hanson-Young called the move illegal and said it would inevitably be overturned by the courts.

“This is an extreme abuse of the Immigration Minister’s power to detain people. Detention is only allowed to prepare for the purpose of a person’s removal from Australia or to hold someone while processing their claim for a visa,” she said.

“The fact that the government is holding pregnant women on a bus in temperatures above 30 degrees is extremely concerning.” The Department of Immigration and Border Protection declined to comment. A spokesman for Immigration Minister Scott Morrison could not be reached for comment.

Australia’s tough policies aimed at stopping asylum seekers include sending them to camps in impoverished Papua New Guinea and Nauru, where they face long periods of detention while they are processed.

The policies have been heavily criticised by the United Nations and human rights groups.

On Saturday, Australia said it had intercepted a boatload of Sri Lankan asylum seekers off the coast of Indonesia, handing back all but one to Sri Lankan authorities, who arrested them for breaching immigration laws.

The Sri Lankans are the first to be turned back in five months as Australia’s highest court hears a test case challenging the government’s right to intercept asylum seekers’ boats outside its territorial waters.