Rugby player Israel Folau has drawn anger for linking Australia's bushfire crisis to the nation's same-sex marriage and abortion laws.

Folau, who was sacked by Australia in May for making anti-gay remarks on social media, described the fires as a "little taste of God's judgement".

Six people have died since last month in blazes raging in eastern Australia.

Prime Minister Scott Morrison condemned Folau's remarks as "appallingly insensitive".

"He is a free citizen, he can say whatever he likes but that doesn't mean he can't have regard to the grievance [and] offence this would have caused to the people whose homes have burnt down," Mr Morrison told reporters on Monday.

Folau, who is Christian, gave a sermon in his Sydney church on Sunday in which he said Australia's decision to pass abortion and same-sex marriage laws had gone against "God's word", adding the nation needed to "repent".

"Look how rapid, these bushfires, these droughts, all these things have come, in a short period of time. You think it's a coincidence or not?," he said.

His comments sparked outrage from many Australians online, who noted the widespread devastation of the fires.

He was also criticised by high-profile local figures who had previously supported him.

"Israel, button up," said broadcaster Alan Jones on his radio show on Monday. "These comments don't help."

Rugby Australia (RA) sacked the former Wallabies player in May after he said on social media that "hell awaits" gay people.

The 30-year-old fullback has been widely condemned for those comments and others targeting transgender people, but he has also received vocal support from Christian groups.

Folau is suing RA over his dismissal, claiming his contract was unlawfully terminated due to his religious beliefs.

Rugby Australia has stood by its decision to sack Folau, saying he breached a players' code of conduct. He was previously one of the nation's highest-paid athletes.