Bath have been charged with breaching Premiership Rugby policy after allowing Taulupe Faletau to play for Wales against South Africa last Saturday.
Premiership rules dictate that clubs should not release non-England players for fixtures that fall outside of World Rugby's international window, as Wales' victory did.
It waived the policy last season as Wales' extra match fell on an Anglo-Welsh Cup weekend but it has taken a stronger stance this time around given Bath were away at champions Exeter in a league fixture.
Faletau's international teammate Rhys Priestland was on the Bath bench as they lost to the Chiefs, while Exeter prop Tomas Francis and Gloucester playmaker Owen Williams were among the players not made available for the match.
"Premiership Rugby confirms that Bath Rugby have today been charged with allegedly breaching Premiership Rugby approved policies," a statement read.
"The allegation relates to the Premiership Rugby Board policy around international duty and specifically Taulupe Faletau being released outside the periods specified in World Rugby Regulation 9."
Bath have seven days to respond to the charge.