Big Brother Australia favourite Josh Moore has decided to quit the reality show after receiving news of his brother's death, Channel Nine announced in a statement.

Moore learned of his brother's death Wednesday night, just when the housemates were getting ready to sleep.

Josh's brother Toby, 32, reportedly died of heart attack. He was Josh's only sibling.

"Josh then spent the night outside the house with his family where he made the decision to leave the Big Brother competition and go home to support his family at this sad time," Nine's official statement read.

"Further announcements about the Big Brother shows will come later today."

Voting for this week's evictions had been closed out of respect for the grieving Moore family, BrisbaneTimes.com.au reported.

"All voting revenue raised will be donated to The Salvation Army on the request of Josh and his family," BrisbaneTimes quoted a spokesperson from Nine Network.

Moore, a 28-year-old surfer and musician, had never been at risk of eviction at the Big Brother house.

Big Brother Australia: Sympathies for Josh Moore on Twitter

Josh is perceived to be one of the coolest mates in the competition. He is believed to be a favourite to win the reality show this year.

Big Brother viewers, including fans who made a Twitter account for Big Brother host Sonia Kruger, expressed their sympathies for the family of Josh and Toby Moore.

@SoniaKrugerr: Sorry to hear about the devostating news about Toby Moore. (Josh Moore brother) @bbau9 @Channel9 #BBAU

@TeamZoeBBAU: Wow, some tragic news from Josh. #TeamZoe would like to send condolences to Josh and the Moore family.

@FitzySA: Absolute tragedy. Thinking about Josh and the Moore family.

@AlexMavroidakis: A very sad day for all involved in #BBAU - All our love and support to Josh and the Moore family.