Christine Forster, the sister of Australia’s Prime Minister, has revealed that she has proposed to her partner Virginia Edwards.

Yesterday, the pair revealed their March engagement in the Australian outback to New Idea, an Australian weekly magazine.

She told the magazine: “We got engaged when we were away with friends on a trip to Broken Hill”.

Ms Forster, a mother of four, said she will only start making concrete wedding plans when she is able to enter a legal union and admits it could be a “long wait”.

Equal marriage remains banned at a federal level in Australia.

Ms Forster, a Liberal Party councillor in Sydney, belongs to the same party as her brother, Australia’s Prime Minister Tony Abbott.

Despite having a gay sibling, Mr Abbott continues to oppose equal marriage and is currently supporting a legal challenge to prevent the Australian Capital Territory from legalising the measure.

Last week, Mr Abbott said that the ACT court challenge was about upholding the Australian constitution and about preserving a “uniform approach throughout the commonwealth” to marriage laws.

But despite their differences, Ms Foster wants her brother to attend the wedding and believes his views on equal marriage may end up shifting.

“It will be close friends and family. Tony and Margie will definitely be there,” she said.

A same-sex marriage bill is due to be voted on in the ACT on Tuesday, potentially paving the way for equal marriage rights across Australia.