"While we cannot share specific details, obviously we would love to have Sonny remain with New Zealand Rugby in the future and we are in negotiations currently to try to achieve this," he said.
"The discussions are complex but also open and transparent. We have a great relationship with Sonny and his management, but we're taking nothing for granted as we are acutely aware he is sought after the world over for his skills, professionalism and profile. We're putting our best foot forward and working very hard to keep him here."
Ambitious Toulon owner Mourad Boudjellal recently confirmed he had met Williams' manager Khoder Nasser, who also looks after the interests of Quade Cooper, a present Toulon player.
However, Boudjellal, not known for his discretion as far as the French media are concerned, is apparently not getting ahead of himself.
He said recently: "I have no idea whether he is coming or not and I can only confirm that the world champion has lots of choices."
That comment alone suggests the normally wildly optimistic Boudjellal is not holding out much hope.
A return to the NRL and the Sydney Roosters is also an option for Williams, but that also appears to be looking increasingly unlikely.
Instead, Williams could be turning out for the All Blacks in the Rugby Championship in September, shortly after his trip home from the Olympics. But New Zealand Rugby won't be celebrating any retention until he puts pen to paper.