Stade Francais have demanded England release flanker James Haskell immediately so he can play in Saturday's clash with Toulouse.
The 24-year-old has started all of England's three RBS 6 Nations matches so far but, playing outside of England, is not subject to the Rugby Football Union's player release contract with Premier Rugby. The RFU claim they have negotiated an individual deal with Stade - but the Top 14 club deny that any such agreement exists and insist the player is duty-bound to report for training this week.
A strongly-worded statement on their official website, www.stade.fr, read: "On Monday, Stade Francais - finding England international James Haskell absent from training - asked the back-rower to return immediately to Paris."
The statement continued: "This period is not provided for in the IRB's international windows and Stade Francais have a big match against Stade Toulousain on Saturday.
"The RFU responded that they will refuse to release Haskell on the grounds that an agreement was signed between them and Stade Francais. No agreement has ever been signed with the RFU, contrary to what they claim. If it is so, the RFU can produce this so-called agreement.
"The RFU have surely confused us with other clubs such as Toulon, who had to accept an agreement for this season relating to Jonny Wilkinson.
"Therefore, Stade Francais are ordering James Haskell, who has already missed two training sessions, to kindly rejoin his club urgently.
"The RFU have signed agreements with English clubs, whom they reimburse for placing their international players at their disposition outside of IRB international windows.
"This is not the case for French clubs who, thus, do not have to fund the preparation of the England team."
Haskell has featured in England's last 20 games in succession and scored his first two international tries in the Six Nations opener against Wales.