Tony Abbott has thrown his support behind his openly lesbian sister in her bid for a council seat in Sydney.

The Australian Opposition Leader announced his support for his sister, Christine Forster, in a letter to voters.

“My sister Chris is one of the bravest people I know,” the letter read. “It takes real guts for a basically conservative person to admit she’s gay and to build a new life based on who she really is.

“She’s managed to negotiate the inevitable hurt in a way that’s kept the love of her vast network of family and friends.”

Abbott said his sister, who lives in Sydney’s Surry Hills with her partner Christine, could rejuvenate the city.

“She’s running for Sydney City Council on her policies, not on her sexuality, but the way she’s handled this shows the character she’d bring to public life,” he said.

However, Abbott told The Sunday Telegraph his support for his sister did not change his views on marriage equality.

He remains staunchly opposed and is denying his MPs a conscience vote on the issue in Australian Parliament.

“We’ve had a lot of interesting discussions and we’ll keep those discussions going, but fundamentally I want to be a politician that keeps my commitments,” he told the Telegraph.

“We went into the election with a position and as far as I’m concerned, that’s the position we will keep.”

Forster, 47, is on the Liberal ticket with mayoral candidate Edward Mandla.