Home Affairs Minister Peter Dutton's written directions to his department on when to refer visa detention cases to him for ministerial intervention state he's not actually bound by his own guidelines.

Mr Dutton faced more questioning on Tuesday over his decision to use his ministerial discretion powers to grant visas on public interest grounds to two young tourists who came to Australia to perform baby-sitting duties in June and November 2015.

Greens MP Adam Bandt asked the minister during question time to categorically rule out any personal connection or relationship with the intended employer of either of the au pairs.

"The answer is yes, Mr Speaker. I haven't received any personal benefit. I don't know these people. They don't work for me," Mr Dutton told the lower house.

He went on to attack Mr Bandt and his colleague Nick McKim in the Senate for what he said was hypocrisy because they regularly refer cases to him for ministerial intervention.

"If the honourable member has some allegation to put, go outside into the public domain, put the allegation, and I will deal with it in the usual way," Mr Dutton said.

Former deputy prime minister Barnaby Joyce, who last month lost his cabinet post and the Nationals Party leadership following a scandal, defended his colleague on Tuesday morning.

"If there's one thing I'd never doubt, it's Peter Dutton's integrity," Mr Joyce told reporters in Canberra.

Meanwhile, AAP has obtained Mr Dutton's April 2016 guidelines for his department's "complex case resolution" section.

Mr Dutton stipulates cases in which people are detained under migration laws can be referred to him under certain circumstances, including:

* The person has individual needs that can not be properly cared for in a secured immigration detention facility, as confirmed by a qualified professional treating the person.

* There are strong compassionate circumstances such that a failure to recognise them would result in irreparable harm and continuing hardship to an Australian citizen or an Australian family unit (where at least one member of the family is an Australian citizen or permanent resident), or there is an impact on the best interests of the child in Australia.

* The person has no outstanding primary or merits review processes in relation to their claims to remain in Australia but removal is not reasonably practicable.

* There are compelling or compassionate circumstances which justify the consideration of the use of my public interest powers and there is no other intervention power available to grant a visa to the person.

The guidelines state the department must balance the above considerations with adverse information such as criminal history, health risks and person's behaviour in immigration detention.

But the second-last clause in the guidelines say: "I am not bound by these guidelines. I am able to consider a case whether or not it has been brought to my attention under these guidelines. When I consider it appropriate, I will seek further information."

A former department official told AAP under the ministerial discretion powers "the minister is God. He can do whatever he likes."