France's club rugby president, Serge Blanco, has encouraged Sonny Bill Williams to finish the NRL season with the Bulldogs before moving to Toulon.

Blanco, a former Les Bleus fullback with 93 Test caps, said he was disappointed the 22-year-old Williams had not honoured his contract with the Bulldogs before going to France for a proposed switch to rugby union.

"In my view, (Williams) should finish his season with his club in Australia and then come to France," Blanco told Fairfax.

"I find it funny and bizarre that a player would break his contract in the middle of the season to go somewhere else. There is a rule in the French competition that a player can finish his season in Australia and then come to France midway through the season."

Blanco, whose Ligue Nationale de Rugby controls the Top 14 and Pro D2 competitions in France, said he had not yet been contacted by NRL chief executive David Gallop over the issue.

Blanco also said Toulon had not consulted him about Williams' reported recruitment.

"No one is in the know at the moment," Blanco said. "I don't know Sonny Bill Williams, but in the last few days I have heard his name a lot. I have received no official demand from the Toulon club. I am waiting to see what will happen."

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