Northampton Saints could face a fine after they released George North to play for Wales against Australia on Saturday.
The 21-year-old Lions winger has a clause in his contract that permits him to play in every Welsh Test and attend national team training camps.
However, Premiership Rugby's rules state that non-England players are not allowed to be released by their clubs outside of the official International Rugby Board window for Test matches.
North, who moved to Franklin's Gardens in the summer, has not played for the Saints since October 20.
