England's leading rugby clubs have been told not to allow their stars to play in the showcase match between the Barbarians and World Cup-winners South Africa at Twickenham next month.
The instruction has come from Premier Rugby, whose chief executive Mark McCafferty has insisted that approaches have been made to players to represent the Baa-Baas on December 1.
"I'm not surprised they've approached players, but I'm disappointed because they came to us centrally and we gave them the clear position that the board of the Premiership had confirmed," he said.
"It's disappointing if players have been approached when that is the case but we still expect the clubs to support the position."
The match clashes with the final weekend of group matches in the EDF Energy Cup - the Anglo-Welsh club tournament - where eight English sides still have a mathematical chance of qualifying for the semi-finals.
McCafferty said: "They have to understand that during the season it is not possible these days.
"We have no stake or interest in that game. Our message to the Barbarians has been for some time that we are very willing to work with them on post-season games during the summer, but it's very difficult, if not impossible, for us to release players during the season for those sort of representative fixtures."
McCafferty insisted that individual players should "absolutely" put their clubs first and that clubs should refuse to release anyone.
"That's an EDF Energy weekend, one they are committed to. As far as the clubs are concerned the communication to the Barbarians has been that we cannot and won't release players for that game," he added.
McCafferty claimed Premier Rugby would "frown" on any club releasing players, stating: "We've had a number of discussions with the clubs over the last few weeks and are not expecting any of the English players to be released. They have enough pressures in terms of their club commitments.
"We do recognise the great cause of the Barbarians, the brand and the charitable causes they support, and we are prepared to work with them on the end-of-season games they traditionally have and on some of the tours they do - but they have to understand that during the season it's not possible.
"Playing one-off fixtures like that during the season isn't feasible."