Independent senator Jacqui Lambie has delivered the Morrison government a major win after voting to scrap laws making it easier for refugees to get medical transfers to Australia.
Repealing the so-called medevac laws restores power to Home Affairs Minister Peter Dutton, giving him the final say on transfers for health reasons.
The laws, which came into effect in March, allowed people in offshore processing to be transferred on the recommendation of two independent doctors.
The coalition denies doing a deal with Senator Lambie, despite her saying she worked on a proposal which couldn't be revealed.
"When I say I can't discuss it publicly due to national security concerns, I am being 100 per cent honest to you," the tearful Tasmanian told parliament.
"My hand is on my heart and I can stand here and say that I would be putting at risk Australia's national security and national interest if I said anything else about this."
Government Senate leader Mathias Cormann denied striking a secret deal with the crucial crossbencher on the medevac repeal bill
"I will not go into private conversations with crossbench senators. We never do," he said in question time.
"What I can say is that there has been no deal to change any policy on border protection or anything else."
Medecins Sans Frontieres - also known as Doctors Without Borders - found 30 per cent of the 208 refugees and asylum seekers the group treated in offshore processing had attempted suicide.
Some 60 per cent considered killing themselves.
MSF's executive director Paul McPhun said repealing medevac flew in the face of patients' best interests.
"A lifeline has been ripped from the hands of people whose only crime may have been seeking safety from persecution," he said.
Prime Minister Scott Morrison celebrated scrapping the medical transfer regime.
"We've always understood that that type of loophole doesn't strengthen our borders, it only weakens them," he told reporters in Canberra.
Australian Medical Association president Tony Bartone condemned the decision.
"I'm not worried about the politics of this issue, I'm worried about the people, the patients here at the centre of this system," he told the National Press Club.
It's understood the government may have agreed to send refugees from offshore processing to New Zealand after a similar arrangement with the US ended.
New Zealand Immigration minister Iain Lees-Galloway said there had been no fresh talks on the proposal.
"The offer remains on the table," he said.
"It's on the table and we're happy to help if they want to take the offer up. We'll wait and see."
Labor and the Greens accused the government of doing a secret deal with Senator Lambie.
"The parliament and the Australian people have a right to know what this secret deal is," the opposition's home affairs spokeswoman Kristina Keneally said.
"There's been a deal between the Morrison government and Senator Lambie to drive a stake through the heart of medevac."
Greens leader Richard Di Natale said there were conflicting accounts.
"We had minister Cormann say that there was no deal. Now we've just heard Senator Lambie say there is a deal," he said.
"Who's lying, minister Cormann? Are you lying? Or is Senator Lambie lying?"
Earlier in the week, Senator Cormann and Senator Lambie both ruled out horse trading on the medevac repeal bill.