Peter Dutton has said women have been “trying it on” in claiming they were raped and needed an abortion as part of a ploy to get to Australia for medical treatment from refugee centres on Nauru.

Speaking to Sky News, the home affairs minister claimed the women then changed their minds on arriving in Australia and sought a legal injunction to prevent their return to offshore detention.

Dutton also confirmed a number of medevac cases have been rejected by the immigration minister, with some of those rejection then overturned by the independent medical panel, which includes the government’s chief medical officer.

More than 30 people have been brought to Australia for medical treatment, under the recently introduced medevac laws, which were stridently opposed by the Coalition. Another 40 during the same time period have arrived under the original medical transfer process, which has brought about 1,000 people to Australia.

Speaking to Sky News on Thursday, Dutton said “you could question whether people needed medical attention”, and accused them of simply seeking to get to Australia and obtain legal injunctions preventing their return.

“Some people are trying it on,” he said. “Let’s be serious about this. There are people who have claimed that they’ve been raped and came to Australia to seek an abortion because they couldn’t get an abortion on Nauru. They arrived in Australia and then decided they were not going to have an abortion. They have the baby here and the moment they step off the plane their lawyers lodge papers in the federal court which injuncts us from sending them back.”

In 2016 a federal court judge found Dutton had breached his duty of care to a woman who became pregnant as a result of rape, and exposed her to serious medical and legal risks in trying to avoid bringing her to Australia for an abortion.

The medevac laws streamline and codify processes for refugees and asylum seekers who require care which they are not receiving in PNG or Nauru, and follow several years of complaints that transfer requests under the previous system were being blocked or ignored by the Australian and Nauruan governments.

On Thursday Dutton said he was sure that some of the 1,000 or so people from offshore processing who had come to Australia for medical treatment over the years were of “bad character”.

“I don’t think there is any question about that,” he said.

He would not provide details of those cases, nor would he say what “bad character” meant.

“I’ll go into those details at the appropriate time.”

Asked if any of the 30 people medically evacuated to Australia were not actually sick, Dutton said: “I think you want to have a look at each of the cases.”

Dutton told Sky News that the doctors who assessed patients for medical evacuation were not government appointed and many had “advocacy backgrounds”.

The minister also railed against this week’s federal court decision that set a precedent allowing for doctors to assess a medevac applicant’s medical files, without needing to consult the patient in person or remotely.

The federal court case noted it was not disputed by the home affairs department that the two doctors in question were acceptable assessors.

Dutton suggested the existing transfer processes – under which the government has been accused of delaying transfers for up to five years for some people – gave the government greater capacity to return people once they received their medical attention.

A number of asylum seekers and refugees have sought legal injunctions to stay in Australia under those processes.

He did not explain why it was different under the medevac law.

Labor’s shadow home affairs minister, Kristina Keneally, earlier said the government already accepted “desktop reviews” of medical records for student visas, and in tender documents specifically sought doctors to conduct desktop reviews for the medivac process.

Keneally also quoted former Liberal prime minister Malcolm Turnbull to say “we know everything there is to know about these people”.

She said every asylum seeker and refugee in offshore processing environments had already gone through a security assessment, although not all have been cleared.

She said the government had put forward no evidence for why the legislation should be repealed.