Federal Government Cabinet Minister and key adviser to the Prime Minister Arthur Sinodinos has revealed he has been diagnosed with cancer.
The Industry Minister has been on medical leave for the past two weeks and has said he hopes to return to work this year.
Senator Sinodinos has been undergoing treatment but has not revealed the type of cancer he is fighting.
Prime Minister Malcolm Turnbull said his colleague was going well but he has "obviously got some tough treatment ahead of him".
"He has a very good prognosis, he is a wonderful colleague, a great Cabinet minister, a great public servant — a servant of the people throughout all his life and I am very confident that he will be fit and back on deck very soon," Mr Turnbull told Melbourne radio station 3AW.
Senator Sinodinos took on the industry portfolio early this year.
He is a significant figure in the Government because of his long political experience including as chief of staff to prime minister John Howard.
He has spent six years as a Senator and held portfolios including Assistant Treasurer and Cabinet Secretary.
There is already significant disruption in the ministry because of the citizenship questions over three senior Nationals.
Former cabinet minister Matt Canavan has already resigned from the ministry but would be expected to return if he is cleared by the High Court.
Deputy Prime Minister Barnaby Joyce and Regional Development Minister Fiona Nash have stayed in the ministry but will also have their eligibility tested in the High Court next week.
Special Minister of State Scott Ryan has also been on extended leave because of an undisclosed illness.