PARRAMATTA are threatening legal action against the Canberra Raiders and the NRL if Josh Papalii backflips on his three-year deal to join the Eels.

The development emerged as Raiders officials urged Papalii to make a call on his future before this week's opening round of the season.

Creating further tension between the two NRL clubs, The Sunday Telegraph can reveal that Eels officials are getting legal advice as the Raiders attempt to convince Papalii to stay in the capital.

Papalii agreed to the deal with Parramatta three weeks ago, signing the contract with his mother by his side. He told Eels officials he was excited about the opportunity to join the club.

Despite reports that the Raiders are disappointed with the way the negotiations were handled, Parramatta officials remain confident that the deal was signed without any concern the 20-year-old would change his mind.

"Three weeks ago, Josh was over the moon to be joining the Parramatta Eels. Today he's being swayed into breaking a legal contract," a Parramatta source said last night.

"Josh has a made a very courageous decision to sign this deal in good faith and take up a new challenge in Sydney.

"He's looking after his mum and family's future and he shouldn't have to be in this position where the Raiders are pressuring him into making a decision before Round 1.

"Josh has made his decision to join Parramatta, why would you place more pressure on him?

"It's unfortunate this continues to drag on. But the Raiders and the ARLC must understand if Papalii is swayed into breaking a legally binding contract we will be taking legal action.

"We sincerely hope for the game's sake it doesn't get to that stage, but that's how much Josh means to our club and at the end of the day the contract was signed in the knowledge he would be joining us in 2014. The last thing the NRL need is a legal wrangle in the middle of the season."

The Raiders are attempting to exploit a salary-cap loophole which states no contract can be registered until Round 13 of the new season. Eels officials also refute Canberra claims that Papalii had only signed a letter of intent, not a contract.

Papalii is yet to speak publicly about his decision to join the Eels but said in a statement announcing the deal: "The time I have spent with the Canberra Raiders have been the best of my life. The club and the fans have been so good to me and my family and I will always be grateful.

"Heading to Parramatta next season is a new and exciting challenge, they are a club on the rise and I am looking forward to being a part of what Ricky Stuart and the team up there are doing."

Eels coach Ricky Stuart said Papalii was the perfect fit for the Eels.

"Josh is an outstanding young footballer and will bring with him all the attributes we are looking for in a player at Parramatta."