Wigan have accused Catalans Dragons of making an illegal approach to Sam Tomkins after confirming he is to leave the club at the end of the season.
The Warriors had an option to keep hold of the 29-year-old former England full-back for 2019 but sought to negotiate a reduction in his terms and in the end agreed a parting of the ways.
The move had been mooted for several weeks and Wigan executive director Kris Radlinski criticised the actions of the Catalans for approaching Tomkins before the anti-tampering deadline of May 1.
"It came as a surprise to us that another club had engaged with Sam so early in the year when the deadline for approaching a player under contract is at the end of April," Radlinski said.
"We have made our feelings known about this to the club involved."
It will be the second time Tomkins has left his home-town club for a new life after joining New Zealand Warriors at the end of the 2013 season for a world record transfer fee of around £700,000.
He cut short his stay in Auckland, however, and rejoined Wigan on a four-year deal under the new Super League marquee player rule.
Radlinski said: "Wigan had an option on Sam's contract to keep him as one of our marquee players for 2019.
"After a great deal of consideration, taking all of the factors into account and following an open and honest conversation with Sam, the club felt that the option salary set when Sam returned from New Zealand was too high and opted instead to offer a substantial new four-year deal in its place.
"This new deal was still one of the top three contracts that the club has offered anyone in the past 10 years and was as a marquee player still.
"Sam subsequently told us that the opportunity for him and his family to experience a different culture and lifestyle and to see his kids speaking another language was something that really appealed to him.
"In situations like this, there is nothing that the club can do other than be generous, fair and wish the player well.
"Nothing lasts forever – and as a club we have to constantly evolve. Players will come and players will go.
"All we ever ask is that players give their all for the badge whilst they are at Wigan.
"Sam has done that and more – and will continue to do so until he can no longer.
"Being the competitive and ultimate professional that he is, I have no doubt that Sam will want to go out as a winner this season."
Tomkins, who has won 23 England caps and was named Man of Steel in 2012, will join his old Wigan team-mates Michael McIlorum and Lewis Tierney in Perpignan.
Wigan have a ready-make replacement in former Catalans utility player Morgan Escare and are thought to have lined up a move for former Leeds and Castleford full-back Zak Hardaker, whose 14-month drugs ban ends in November.
Radlinski added: "Discovering, developing and getting the best out of players like Sam Tomkins is what we do here at Wigan. That will never stop."