Sydney - Former Wallaby bad boy James O'Connor is leaving Sale Sharks to make a last-gasp attempt for inclusion in Australia's Rugby World Cup squad, the English Premiership club said on Wednesday.

Sale said it had released O'Connor, who turns 29 on Friday, from his contract with immediate effect so he could pursue his dream of again playing for the Wallabies.

"James has signed a contract with Rugby Australia which will allow him to be selected for the World Cup later this year. He leaves Manchester with the full support of the club," Sale said in a statement.

O'Connor was the second-youngest Wallaby ever when he made his debut at 18 in 2008, but a string of off-field incidents brought his international career to a crashing halt on 44 Test caps.

The utility back was only 23 when the Wallabies tore up his contract in 2013 after he was prevented from boarding a flight from Perth to Bali for being drunk.

His chequered past also includes being arrested and fined in Paris in 2017 during a cocaine bust while playing for Toulon, before a move to Sale later that year.

Sale director of rugby Steve Diamond said under the club's guidance O'Connor went to "extreme lengths to improve himself both mentally and physically, and has been successful in both areas".

O'Connor thanked Sale for the support he had received at a difficult time.

"Without the experience at Sale I would not have been able to grow and find my true self in a chaotic period of my life," he said.

Rugby Australia officials have reportedly met with O'Connor in recent weeks and are convinced he has matured and deserves a chance to revive his international career.

He has signed a three-year deal with the Reds, according to Fox Sports, although neither the Super Rugby club nor Rugby Australia have confirmed the move.

Australian great Matt Giteau admitted O'Connor "rubbed people up the wrong way" early in his career and said senior Wallabies should have done more to rein in the brash youngster.

But he said O'Connor was now team orientated, willing to learn and aware of his past mistakes.

"Returning to the Wallabies is something he desperately wants now," Giteau wrote on playersvoice.com.au. 

"If you've got someone of his talent who's desperate to play for his country... it makes sense to bring him back in.

"It would be a waste if he didn't get another opportunity - for him and Australian rugby."