England's final group game against Tonga on Friday is a winner-takes-all clash for a place as Pool A runners-up, and a likely quarter-final against Australia in Marseille on 6 October.
Sarries chief executive Edward Griffiths says the prop's new deal is illegal and irrelevant and has taken up Tonga'uiha's U-turn with the governing body of the Guinness Premiership, who have now asked for written reports from both clubs.
World No.2 Nadal is struggling with the knee injury he picked up Wednesday's quarterfinal win over Jo-Wilfred Tonga, where he was taken to three hard-fought sets.