England stars playing in France next season will not be able to challenge the Rugby Football Union over a warning about their international careers.

Damian Hopley, chief executive of the Professional Rugby Players' Association, last night received legal advice over a letter the RFU sent to England's elite player squad.

Francis Baron, the RFU chief executive, made it clear in the letter that players will only be considered for England if they have release periods included in their contracts.

However, RFU officials dismissed suggestions that a close call between a player in England and one in France would favour the home-based one. This did not form any part of Baron's two-page letter.

Hopley said: "As a precautionary measure we consulted a legal expert and there were no major issues raised concerning the letter from the RFU. The advice was that a player would struggle to win any case claiming it was a restrictive action."

England stars James Haskell, Riki Flutey and Tom Palmer are quitting Wasps to join fellow England stars Steve Thompson and Andy Goode in French rugby where higher wages are being offered by the leading clubs. English clubs are restricted by a wage cap which does not exist in France.