Toulon president Mourad Boudjellal says the French club will seek "substantial compensation" from Quade Cooper if the Australian does not honour his contract.
The saga that started back in April, when the European champions confirmed the signature of the Wallaby fly-half, continues to drag on.
On Sunday, it was revealed that Cooper had inked a new four-year deal with the Australian Rugby Union with the aim of playing at the 2016 Olympics rather than join Toulon.
The Top 14 champions have always insisted that the Cooper deal was signed and sealed and now look set to take legal action against the 27-year-old, who will have to buy his way out of the French contract.
"Quade Cooper has signed a contract and the document was submitted in due form to the National League," Boudjellal told local newspaper La Provence.
"This contract has been registered with the LNR. […] Cooper confirmed the commitment that was made because he also signed a League contract.
"I do not know the exact amount of the contract price, but a compensation clause was included in the first agreement with an established tariff if the player did not sign the contract to follow.
"If Quade Cooper does not respect this contract, the compensation clause will come into affect and the amount will be very high."
Cooper currently sits on 53 Test caps, meaning he falls short of the 60 required to be eligible for Australia while playing overseas, but he is expected to reach that threshold before the end of the World Cup.