Neymar swapped Barcelona for Paris in a blockbuster £200m move during the summer, although legal wranglings have soured the relationship between club and player, with the Catalan outfit refusing to pay a £23m loyalty fee to Neymar's father.
Spanish publication AS reports that the Brazilian has instructed his lawyers to take strong action against his former employers, including campaigning for them to be booted out of the Champions League.
However, UEFA is understood to have quickly ruled out any prospect of Barcelona being banned from Europe's premier club competition.
Barcelona are also suing Neymar for an alleged breach of contract regarding his move, demanding the return of a contract renewal bonus.
Neymar, who scored 105 goals in 186 appearances for Barcelona, has hit the ground running in France with eight goals in as many games for PSG.