Neymar has filed a lawsuit against Barcelona via football's world governing body, FIFA, with Spanish media saying it revolves around an unpaid loyalty bonus of 26 million euros ($30.69 million), which was included in the last contract he signed with the Catalan club late last year.

FIFA confirmed to the Reuters news agency that it had "received a claim from Neymar against FC Barcelona" and was looking into the matter.

This comes two days after Barcelona announced that they were suing the Paris Saint-Germain player in an effort to recover an already paid bonus.

"In the lawsuit, the club demands the player return the already paid sum for his contract renewal as he has not completed his contract; 8.5 million euros in damages; and an additional 10 percent because of delayed payment," Barcelona said in a statement.

The management group that represents the Brazilian forward, N & N Consultoria, responded with a statement issued on Tuesday in which it said that the player had in fact fulfilled the terms of the contract.

World-record transfer

This is just the latest chapter in an increasingly bitter rift between Barcelona and its former star, who smashed the world transfer record earlier this month when PSG triggered the 222-million-euro escape clause in his contract so that he could move to the French capital.

Following PSG's 6-2 win at home to Toulouse last Sunday, Neymar sharply criticized Barcelona's board of directors.

"I am disappointed with them. I spent four very happy years there and left happy, but not with them," he said. "For me they shouldn't be in charge of Barcelona. Barca deserve much better and everyone knows this."