Governing body the RFU have an agreement with English clubs over the release of players for international get-togethers but this doesn't apply for French clubs.
Stade Francais duo James Haskell and Tom Palmer are expected to attend the camp but could return to France early to star in the Top 14 game against Bourgoin.
Louis Deacon, Geoff Parling and Matt Mullan will all be absent though as they continue to recover from injuries at their respective clubs.
Coach Martin Johnson said: "We believe that these have been the right decisions to take after close and amicable consultation with the clubs concerned.
"We will continue to have regular contact and, subject to fitness, look forward to seeing all of the players when we meet again at the end of October ahead of the Investec internationals."