Josep Maria Bartomeu, the president of Barcelona FC, has denounced the world governing body, FIFA, for punishing his club over a breach of rules on the transfer of foreign under-18 players, saying they are victims of a "grave injustice".

FIFA announced on Wednesday it had banned the Spanish champions from the transfer market for two consecutive windows and fined them 450,000 Swiss francs (£304,000) and the Spanish football federation 500,000 Swiss francs (£338,000) after FIFA found they had also breached rules on the transfer of minors.

Barcelona denied wrongdoing and said they would move to have the transfer ban suspended until their appeal is heard and would take the case to the Court of Arbitration for Sport (CAS) if necessary.

Bartomeu fiercely defended the Catalan club's La Masia academy, which has produced the likes of Lionel Messi, Xavi and Andres Iniesta, and said the club would push ahead with plans to buy at least a goalkeeper and a central defender in the close season.

"We are outraged and the victims of a grave injustice," Bartomeu said. "With this sanction, FIFA is punishing a model that has existed for 35 years and which is the essence of this club. FIFA knows that we do things well and we look after the children and give them an education that perhaps they wouldn't get in their own country.

"We are not prepared in any way to give up our educational model. We have defended, continue to defend and will always defend the rights of minors. Hands off La Masia, that's the message we want to send to our members and fans, hands off La Masia. We will fight until the end to protect this model because it has made our first team become a leader in world football. We have absolute confidence in our lawyers and they tell us we have good grounds to think that the sanction will be lifted."

FIFA's punishment was the latest blow to the club and came after Bartomeu's predecessor, Sandro Rosell, was forced to step down in January amid allegations of mis­appropriation of funds and tax fraud linked to the signing of the Brazil forward Neymar. Rosell has always denied any wrongdoing.