The prime minister denies doing a deal with independent senator Jacqui Lambie to secure her crucial support.

"The only undertaking we've given is to implement our policies - that is it," he told reporters in Canberra on Wednesday.

Senator Lambie offered to help repeal the so-called medevac laws on one condition.

Her condition remains a secret.

"I put to the government a proposal and since then we have worked together really hard to advance that proposal," she told parliament.

"As a result of that work, I am satisfied, I am more than satisfied, that the conditions are now in place to allow medevac to be repealed."

It is believed the government may have secured her vote by offering to send refugees from Nauru to New Zealand, after a similar resettlement deal with the United States is completed.

New Zealand has long offered to take 150 asylum seekers per year from Australia's offshore detention regime.

But the government has steadfastly refused to take up the offer, citing national security concerns.

Repeatedly asked if any assurance involving New Zealand was given to Senator Lambie, the prime minister refused to provide a direct response.

"She has the assurance that the government will implement its policies," he said.

"The government is always looking at ways in which it can resettle those who are on Nauru.

"We will continue to use the arrangements that we have in place to be able to resettle people and that is the assurance that we have provided."

Mr Morrison said repealing the medevac laws, which gave doctors a greater say in bringing sick refugees to the Australian mainland, would restore integrity to border security.

"We have always taken the actions necessary to ensure that Australians can have confidence in the way our borders are managed," he said.

"We've always understood that that type of loophole doesn't strengthen our borders, it only weakens them."

Australian Associated Press