Hamilton - Sonny Bill Williams wants to be rugby league's highest paid player if he returns to the NRL.

According to a report in Rugby League Week, the All Black wants about $800 000-a-year (R6.3m) to return to league from rugby union, will only accept a one-season deal and must be free to continue his professional boxing career in league's off-season.

An un-named coach is reported to have said that Williams's agent Khoder Nasser "told us the only way Sonny Bill would come back to the NRL was if he got a promise that he would be getting the most money of anyone in the game.

"That was one of a host of conditions he set down. It was about at that stage that we lost interest."

Williams is off contract with the New Zealand Rugby Union at the end of the year, and reports last month suggested that he was close to signing a deal for 2013 with the Sydney Roosters.

The Wests Tigers are also said to be keen on Williams.

The 26-year-old played 73 games for the Bulldogs before a controversial switch to play rugby union in France for Toulon.

He then signed with the NZRU and has played Super Rugby for the Crusaders and Chiefs, as well as winning 14 caps for the All Blacks. He was involved in their Rugby World Cup-winning squad last year.

Williams's boxing career has taken in five fights, all of which he has won.