WELLINGTON (AFP) - Code-hopping All Blacks star Sonny Bill Williams confirmed on Friday (Nov 8) he is returning to rugby league and will join the Canada-based Toronto Wolfpack club in a deal that could make him the richest player in either code.

The two-time rugby union World Cup winner said he had signed a two-year deal with the English Super League debutants, but made no mention of the salary package.

However, details of the switch have been leaked to the media over the past week with the 34-year-old said to be earning £2.6 million a year (S$4.5 million) which would be a record deal for either of the rival rugby codes.

"I'd like to thank all those fans in New Zealand and around the world who have supported me," Williams said when announcing the move.

"I'd also like to thank everyone involved in the All Blacks family. I never dreamed that I'd play in the black jersey for 10 years playing alongside some of the legends of the game, and I'm grateful for the support of so many people in helping me grow as a footy player over that time.

"I've enjoyed every moment being with the brothers and that will be the biggest thing I will miss: the camaraderie and fun with my fellow players and being privileged to suit up with them and go out and do what we love. It's been a pleasure."

Williams, who has been plagued by injury in recent years, played 58 Tests for the All Blacks and was a member of the World Cup winning sides in 2011 and 2015.

He played for the All Blacks Sevens at the 2016 Olympics, is a New Zealand boxing champion and is a former New Zealand rugby league international.

He came to prominence playing for the Canterbury Bulldogs in the Australian National Rugby League competition before switching to union in 2010.

He returned to the NRL in 2013 to join the Sydney Roosters and also played in the New Zealand side that lost Rugby League World Cup final to Australia that year before returning to union for a second term.

Toronto - who are backed by the Australian oil tycoon David Argyle - play their first Super League game against Castleford on Feb 2.