Refugee allegations malicious: Morrison

Immigration Minister Scott Morrison has branded allegations two pregnant Iranian refugees were mistreated by staff at a Northern Territory detention centre as malicious.

"The government denies claims of cruelty and mistreatment of the individuals in the strongest possible terms," he said in a statement.

"These are yet more malicious claims by asylum activists."

The claims centre on a stand-off with staff at the Darwin facility after the women and their families refused to get off a bus and enter the centre. The dispute rolled on for about two days before being resolved.

Mr Morrison said the welfare of the two eight months pregnant women, their husbands and one son was monitored and they had access to food, water, amenities, toilets and health professionals.

But refugee advocates say the air conditioning on the bus, parked at Wickham Point detention centre 40km south of Darwin, was turned off.

"On Monday, both pregnant women fainted after the bus was intentionally allowed to heat up," Refugee Action Coalition spokesman Ian Rintoul said on Wednesday.

Hussein, the husband of one of the women, collapsed and was taken to the medical centre in the facility, he added.

Mr Rintoul also disputes the time frame for the end of the stand-off, saying the two women "were dragged off the bus" between 5.30pm and 6pm on Monday, rather than Tuesday morning as reported.

The second man, Adnan, alleges he was physically restrained by four guards as his wife Maryam was taken off.

The two families had been on Nauru for 15 months, and lived in the community for part of that time after being recognised as refugees.

The department has previously denied the group - brought to Australia for the final month of the women's pregnancies - was told they would be living in the Darwin community until the births.

Mr Morrison said the department and detention service provider Serco had acted appropriately toward the women and their families.

"My understanding is they're fine," the minister told reporters in Canberra.