Sydney - Tonga coach Toutai Kefu wants sacked Wallaby Israel Folau to play for the Pacific island nation at the 2023 World Cup and has been in touch about switching allegiances, a report said on Thursday.

The devoutly Christian fullback was fired by Rugby Australia last month for posting homophobic comments on social media in a case that sparked debate about religious expression.

Folau, who is of Tongan heritage, has launched legal action through Australia's employment watchdog the Fair Work Commission.

The 30-year-old had been due to play a key role for the Wallabies at this year's World Cup in Japan, but that dream is now over.

Given he has already represented Australia, Folau cannot switch immediately and play for another country.

But under a loophole in World Rugby regulations, he could apply to play for Tonga's national side if he sits out three years of international rugby and then represents Tonga at Sevens in an Olympic qualifying event.

Kefu, a former Wallabies No 8, is keen to have Folau on board and while yet to speak personally with the 30-year-old, suggested contact had been made with his team.

"We'd love to have him... the next World Cup he'd be available for us hopefully," he told the newspaper.

"It's a long time away, so we'll let the dust settle a bit after his most recent issues. We don't even know if he's going to play again.

"He hasn't indicated where he is going, so we'll wait until the dust settles and then look at those options."

Another enticement is that Folau's brother John, who was on the books of Super Rugby franchise the Waratahs but quit in solidarity with his sibling, is expected to be named in the Tonga squad for the upcoming Pacific Nations Cup (PNC).

This could open the door to him playing for the Pacific nation at the Japan World Cup and beyond.

"We're going to look at him and even may take him to the PNC because we've got some holes in our squad, especially out wide in the backs. There's a good chance he will be part of that squad," Kefu said.

He added that "then we can see whether he is good enough to be part of that Rugby World Cup squad".

John Folau, who like his brother moved to rugby union from rugby league, has not played for Australia, so is eligible for Tonga now.