Toronto Wolfpack are preparing to announce the return of Sonny Bill Williams to rugby league on a record deal for either rugby code.

Williams, who played for the All Blacks at the recently completed Rugby World Cup in Japan, is understood to have advised Wolfpack officials he will join the Canadian club for their historic foray into Super League next season.

An announcement is expected within the next week ahead of an official function and jersey presentation at Canada House in London. 

The signing of Williams on a two-year deal reported to be worth as much as $10 million is a massive coup for not only the Wolfpack but the game in North America and the Super League competition.

With arguably the biggest signing in Super League history in their side, the Wolfpack are set to kick off the 2020 season at Headingley on February 2 as part of a unique double-header that will generate worldwide interest.

The Wolfpack are also set to take their round 5 match against St Helens to London's Allianz Park, the home of Saracens, where the presence of Williams will help attract rugby union fans. 

Wolfpack coach Brian McDermott flew to Japan to watch Williams play in the All Blacks’ semi-final loss to England and table the offer that will result in him become the highest-paid player in rugby league or union history.

The 34-year-old also had lucrative offers from French rugby union clubs but the opportunity to help the ambitious Canadian club make inroads in North America had more appeal.

Williams is regarded as a superstar wherever he has played – league in Australia and union in New Zealand, France and Japan – and Wolfpack officials believe he can have a similar impact for the code as David Beckham did for soccer with LA Galaxy.

Wolfpack officials have already seen an example of his star power - since he was linked to Toronto, there has been a ten-fold increase in the number of Google searches for the club.

Local media in Toronto have also been covering the story of his imminent signing in the past week.

The dual international made his name in the NRL with Canterbury from 2004-08 and was also a part of the Sydney Roosters' 2013 grand final success during a two-year stint at the club.

He switched codes in 2008 to play for Toulon in France’s Top 14 competition before returning to his native New Zealand two years later for the first of his two stints in rugby union and won two World Cups with the All Blacks.

After becoming only the second player to have represented New Zealand in league before union Williams went on to play 58 Tests for the All Blacks.