Controversial rugby league star Willie Mason switched codes on Sunday after signing a one-year contract with big-spending French rugby club Toulon.

The 31-year-old - who can play at centre or in the backrow - had been sacked by his Super League club Hull KR on Saturday just three months into his three year contract after they learnt he had been to Toulon to meet with the club's directors.

Toulon have become known as one of European rugby union's biggest-spending clubs and currently have the likes of England great Jonny Wilkinson and troublesome Wales international centre Gavin Henson in their squad.

They have been reported to have offered Mason 395,000 euros ($A531,000) per year and club president Mourad Boudjellal said they had offered him a year's extension to his contract should he make 15 starts next season.

The former Canterbury, Sydney Roosters and North Queensland NRL player will reportedly play for the Barbarians against England at Twickenham next Sunday and then again against Wales on June 4.

"I'm just so excited to be playing rugby and I'm looking forward to the challenge," Mason told the Sun Herald on Sunday.

"I've certainly jumped in the deep end in agreeing to play for the Barbarians without having any rugby experience."

"If you ask all the boys, I've always told them I've wanted to have a crack at rugby and I've always been the type to jump in at the deep end, and I'm ready to try the best I can to make an instant switch."

Mason has been involved in controversial incidents throughout his career.

These include testing positive for a recreational drug in 2003, being banned for one match after knocking out Great Britain forward Stuart Fielden during a Tri-Nations match in Sydney in 2006 and receiving a fine for urinating in a public place in 2009.

He is the 11th new signing by Toulon, who have had a disappointing season in failing to reach the Top 14 title play-offs.

Their most high profile acquisitions have been Wallabies back Matt Giteau, Springbok World Cup winning lock Bakkies Botha and exciting French international back Alexis Palisson.

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