The coalition of anti-gay marriage and pro-life groups will hold the summit next Wednesday, August 27 on what they are calling 'National Marriage Day', to coincide with the 10th anniversary of Australia's Marriage Amendment Act of 2004 that defined marriage as a union between a man and a woman.

The World Congress of Families (the organisers of the controversial "Pro-Life Olympics") is to hold its regional conference in a Melbourne school hall two days later and BuzzFeed has learned some members will attend the Canberra summit.

The arrival of WCF members at Parliament House will come just weeks after senior Government Minister Eric Abetz got into hot water for publicly supporting more controversial views – such as its belief that there is a link between abortion and breast cancer.

Lectures will be held in the “Main Committee Room” which a Parliament House spokeswoman told BuzzFeed had to be booked by a sitting member.

The spokeswoman would not say which sitting member had booked the space and several Coalition MPs refused to disclose who had assisted in organising the summit.