The prime minister's comment came a day ahead of a court directions hearing in relation to five MPs, and as another coalition MP, George Christensen, faced question about his possible UK citizenship entitlement.
Mr Christensen, who holds the seat of Dawson for the Nationals, says he's confirmed via a British government website he is not a UK citizen.
Mr Christensen's mother, Margaret, came to Australia from Scotland.
Since UK law changes came into force on January 13, 2010, anyone born before 1983 with a British-born mother has been able to gain UK citizenship by registration.
Mr Christensen was born in 1978 in the regional Queensland city of Mackay.
"I have checked my citizenship status both prior to entering parliament and again recently and I can confirm I am not a citizen of any other country," Mr Christensen said in a statement on Wednesday.
"The advice of the UK government, via their online 'Check if you're a British citizen' page, is that I do not have citizenship of the United Kingdom."
However, the gov.uk/check-british-citizen questionnaire does not ask questions about parentage.
Australia's High Court will hold a directions hearing on Thursday in relation to two of Mr Christensen's party room colleagues - Nationals leader Barnaby Joyce and stood-aside cabinet minister Matt Canavan - and One Nation's Malcolm Roberts and the Greens' Larissa Waters and Scott Ludlam.
They have all been referred to the court to test whether they are eligible to sit in parliament under section 44 of the constitution, which bans dual nationals.
Cabinet minister Christopher Pyne said he would not "open a new front" by commenting on Mr Christensen's situation.
"George Christensen will take care of himself. He does so very well," he told reporters in Melbourne on Wednesday.
"The High Court will determine what section 44 means in the modern era and then we can all move on to the things that really matter a great deal more to the Australian public."
