In a huge concern for the NRL, players are apparently queueing up to join Sonny Bill Williams in fleeing the league.

Player manager Steve Gillis made the stunning claim that he had fielded "half a dozen" calls since the weekend from players interested in overseas opportunities.

In a sign Williams' weekend escape to the French rugby union may only be the tip of the iceberg, Gillis said NRL stars were becoming increasingly aware of the riches on offer in the northern hemisphere.

Williams is believed to have been offered a $3 million two-year contract with Toulon, where he would join former Penrith skipper Craig Gower, St George Illawarra centre Mark Gasnier and Panthers winger Luke Rooney in the French rugby union next season.

Asked if news of Williams's departure had led to any of his clients making enquires, Gillis said: "I've had half a dozen calls or emails".

"It's going to be big problem," he said.

"They're looking for our very best players. They'll knock them off one by one.

"I think you'll find if there's four or five this year, there'll be 10 next year, probably 20 or 30 the next year.

"If Sonny Bill Williams is allowed to walk out on his contract and there's no rearguard action, I would expect that other players would want to follow suit."

Asked if he expected more players to sign with French clubs this year, Gillis said, "I do".

Gillis pointed to the fact former NRL stars Ryan Cross, Timana Tahu and Lote Tuqiri played for the Wallabies in Saturday night's Bledisloe Cup win over Saturday night had proved how effective converts could be.

But it would also open the eyes to the world as to the talent on offer in rugby league.

Gillis also warned the threat would not only come from French rugby union, but from clubs across the northern hemisphere.

"I've had some talks with them (French clubs), but it's not just France ... there's Ireland, and there's England and there's Italy," Gillis said.

"We're a tiny speck on the world stage. We play in Sydney and Queensland and we've got a team in Melbourne - there's 28 clubs in the world that you can make money playing league at.

"In union, there's hundreds."

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