Barcelona president Joan Laporta suggests that Kylian Mbappe's new Paris Saint-Germain deal has "distorted the market" and goes against "the principles of the European Union".

Laporta was reacting Wednesday to the French forward's decision at the weekend to reject an offer from Barca's arch rivals Real Madrid and instead sign a contract extension at PSG.

"Players end up being prisoners of money," Laporta told Catalan daily L'Esportiu.

"That's what happens when a club has a state behind it," he argued, in reference to PSG's Qatari ownership.

"It leads you to reflect on the sustainability of football in Europe."

Laporta acknowledged that from a Barca point of view, Mbappe staying put in France was good news.

"A direct rival hasn't been strengthened and for us that's preferable as they can't trouble us even more on the pitch.

"But there's the issue of thinking about the game's sustainability."

Quizzed on the prospect of PSG opening the door for a return by Neymar to Barcelona Laporta said: "He still has four or five years on his contract. Players who've joined clubs like PSG have virtually made themselves slaves. For money."

After Mbappe announced he was staying put at the Parc des Princes Spain's La Liga threatened to take the French champions to court so as to "defend European football's financial model".