A former police colleague of Peter Dutton who wanted help with a detained au pair emailed the immigration minister for help after "a long time between calls".
The Home Affairs Minister ruled out having any personal connection with two people who asked him to intervene to save two au pairs from being deported in separate cases.
In an explanation given to parliament, Mr Dutton said his interventions in the two cases in 2015 were not due to friendships with the people who asked for his help.
"I did not have a personal connection or any type of relationship with the people involved in these matters," he told parliament on Monday.
He tabled the email sent to his public address from Russell Keag, who was in the Queensland police force with Mr Dutton in the 1990s.
"Peter. Long-time between calls," the email starts.
"I need advice on a matter that has occurred today. An Italian student, Michela Marchisio is being held after her visa has been cancelled.
"She was due to stay with my family. There has been a mixup in the visa details."
Ms Marchisio was detained after officials discovered evidence she planned to work, but she was given a tourist visa after Mr Dutton intervened.
Mr Dutton says he did not have a relationship with Mr Keag, who he had not spoken to since they worked in the Queensland police 20 years earlier.
"He wrote an email to my publicly available email account, which can be accessed by anyone online," Mr Dutton said.
"A staff member in my office asked me if I knew this person. My initial response was 'who?'"
Former Australian Border Force commissioner Roman Quaedvlieg has given further evidence to a committee investigating Mr Dutton, alleging Mr Dutton's chief of staff Craig Maclachlan asked for help for "the boss' mate" in the case of a European nanny.
After Mr Dutton said Mr Maclachlan didn't work for him in June 2015, Mr Quaedvlieg provided more detailed evidence about the phone call he received and says it could potentially be a third case.
"I am willing to stake my three decades of distinguished and decorated public service on the absolute validity of this statement," Mr Quaedvlieg said in a statement.
He admits he "may have been honestly mistaken in anchoring that conversation to a date June 2015" but believes that indicates "the only logical conclusion that a second Brisbane ministerial intervention case" might have taken place.
A spokesperson for Mr Dutton said Mr Quaedvlieg has lost his credibility.
"His statement today has no more validity than his fabricated statement from last week. He should provide the detail of the case to which he refers," the spokesperson said in a statement.
The spokesperson said Mr Maclachlan, who still works for Mr Dutton, will not be commenting.
Mr Dutton said he had no contact with "the ABF commissioner" over the June 2015 matter, and neither did anyone in his office.
Mr Quaedvlieg was not technically the commissioner at that time.
Mr Dutton said he also intervened in a similar 2015 case after AFL boss Gillon McLachlan's staff contacted his office.
Australian Associated Press