Cher has apologised to a fan after social media backlash over her photo with Australian Prime Minister Malcolm Turnbull at Sydney's Mardi Gras on Saturday night.

Cher stole the headlines as the iconic singer made an appearance in Sydney for Mardi Gras's 40th anniversary on Saturday night and the first since same-sex marriage was legalised in Australia.

But an innocent selfie with Mr Turnbull, who was attending the event with wife Lucy and New South Wales Premier Gladys Berejiklian, caused a storm on social media.

Welcome to Sydney, Cher! @GladysB Lucy and I and all your fans thrilled to be with you at the 40th Mardi Gras & first since Australia achieved marriage equality. pic.twitter.com/EIYDaq2OTG — Malcolm Turnbull (@TurnbullMalcolm) March 3, 2018

Disgruntled social media users hit back at Mr Turnbull following the selfie, claiming the "harmful" same-sex marriage postal survey placed unwanted pressure on the LGBTQI+ community.

Cher claimed on Twitter her interaction with Mr Turnbull was "compassionate" and he was "proud of everyone at the parade", but ended up apologising to a fan.

I’m not sure what you mean.

The Man I Talked To Seemed PROUD OF EVERYONE AT THE PARADE. Am I Missing. Something⁉️

The Man I TALKED Could Be Reasoned With,The Man I Talked TO Believes In Equal Rights for ALL OF HIS PPL.THE MAN I TAKED TO WILL LISTEN &

HEAR”& 🐝COMPASSIONATE — Cher (@cher) March 3, 2018

Am so sorry. Guess that’s why I have FEW Friends Who Are Politicians.He Seemed Very Open & excited about MARDI

GRAS,AND LGBT COMMUNITY. — Cher (@cher) March 4, 2018

The LGBTIQ community's night of nights dazzled about 300,000 spectators on Sydney's famous Oxford Street with pop superstar Cher making an appearance for the 40th Mardi Gras parade.

Confetti, glitter and rainbow flags lined Oxford Street for Saturday's parade, the first since same-sex marriage was legalised in Australia.

In November 2017, nearly 62 per cent of Australian voted in favour of legalising same-sex marriage in a voluntary postal survey that cost $122 million.

Legislation passed parliament on 7 December and same-sex marriage ceremonies took place across the country from 9 January.