Former Wallabies captain Stirling Mortlock says the ARU must consider allowing players to take sabbaticals between Rugby World Cups in a bid to combat rugby league's forecast raid on the 15-man code.

Mortlock agrees with fellow ex-Wallabies skipper Phil Waugh that new powers enabling NRL boss Dave Smith to lure big-name players pose a serious threat to Australian rugby and says the ARU needs to "think outside the square" to avoid losing its stars.

"He's holding the trump card up his sleeve," Mortlock said.

Mortlock's biggest concern is a possible exodus of Wallabies to rugby league and European and Japanese rugby clubs after the 2015 World Cup in England.

"As a player, that's the pinnacle of our game. There's nothing better than being involved in a World Cup campaign," he said.

"That's a huge drawcard and it's our joker at this stage.

"But after that period of time, I think one of the strategies that we've got to look at is how do we retain our talent?

"That may be going down the pathway of doing similar to what the New Zealand Rugby Union has done.

"They've allowed some of their marquee players to have sabbaticals or time off or actually go overseas for a period of time to play and come back feeling refreshed and ready to go as well.

"So there are examples where it could be done and still retain your quality talent and hopefully lead you into that following World Cup in 2019."

Mortlock pointed to former Wallabies teammate Joe Roff's successful stint with Biarritz in French club rugby after Australia's series win over the British and Irish Lions as a precedent.

"Roffy went away and he ended up winning the Top 14 for Biarritz and when he came back he was physically ready to go but, more importantly, mentally he was rejuvenated and it worked really well for both parties," Mortlock said.

"That was over 10, 12 years ago, but recently New Zealand have done that with their big marquee stars and it's worked really well for them.

"Those sort of strategies and looking outside the square to get the best of both worlds - get a win for all - is something I think we have to entertain because the reality is the opportunity for players to go elsewhere to further their career and the lure of generating more income has been there for a long time."

While Mortlock considers the threat of league poaching rugby's best talent was just "one of a number" of challenges facing the ARU, Waugh said "this new initiative by the NRL is a huge threat", with Israel Folau and Kurtley Beale the obvious targets. AAP