Labor is demanding Tony Abbott explain why he hosted two private parties for a high school reunion and final staff farewell at Kirribilli House days after being deposed as Prime Minister.

Mr Abbott on Friday night held drinks for more than 50 of his old Riverview classmates. He greeted each of the former students at the door to the prime minister's official Sydney residence - Kirribilli House. The class of '75 arrived in two buses.

It has been reported that the event was privately funded and will raise money for charity. Kirribilli House can be used for charitable fundraising.