Belsouer insists he has documentation that can prove United offered youngster Paul Pogba incentives to make the move to Old Trafford.
Pogba is not yet officially registered at Old Trafford.
“We are still pursuing our case,” Belsoeur told The Times.
“It is a very serious case. We are confident that we’ll win because it is in the best interests not just of our club but of sport.
“We spend 5million euros [about £4.3million] on our academy every year out of a turnover of 12million euros. It is a huge investment.
“We do that to give a chance to our players to develop for our first team, not to be an academy for others.
“What is the point of investing in an academy if the players leave at 16? This is clearly a message from Fifa to protect the education system.”
“It is complete nonsense,” a spokesman for United said.
“Everything has been done within Uefa guidelines.”
