PSG claim Barcelona have approached midfielder Adrien Rabiot without their permission.
The Ligue 1 giants have threatened to report Barca to FIFA over the alleged illegal approach, unless Barca back off.
Clubs are not allowed to directly contact players of another side unless that side has given them permission to do so.
But in a twist to the transfer tale, Barcelona claim to have done everything above board in their pursuit of Rabiot.
Transfer news: PSG star Adrien Rabiot could yet join Barcelona (Image: GETTY)
Transfer news: PSG ideally want to keep Adrien Rabiot (right) (Image: GETTY)
They insist, as reported by SPORT, that officials Pep Segura and Eric Abidal travelled to Pairs to inform PSG of their interest in the midfielder.
Tensions between the two clubs have simmered since last summer - before Neymar’s deal was even considered.
PSG were irked by Barcelona’s public pursuit of midfielder Marco Verratti, who was caught in the middle of a transfer battle.
Verratti was snapped holding a front page of Barcelona-based newspaper Mundo Deportivo, with a report of his supposed impending transfer to the Nou Camp on the cover.
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Transfer news: PSG were irked by this picture of Marco Verratii last summer (Image: _)
Neymar scores stunning solo goal in five-a-side game
Transfer news: PSG signed Neymar from Barcelona last summer (Image: GETTY)
PSG reacted furiously and it is thought Barca’s actions over the failed transfer helped fuel the French club’s decision to go for Neymar.
Ligue 1 giants PSG have been under siege from transfer interest this summer.
Barca have wanted Rabiot for a while after failing to make any headway over a deal to sign Manchester United midfielder Paul Pogba.
And Real Madrid are interested in landing one of Neymar or Kylian Mbappe - although a deal for either man this summer appears very slim indeed.
Transfer news: PSG paid £200m for Neymar (left) 12 months ago (Image: GETTY)
Neymar’s future in Paris had been subject to speculation almost as soon as he joined from Barcelona.
Neymar’s father is said to have spoken to Real president Florentino Perez - via intermediary Wagner Ribeiro - regarding a possible move to the Bernabeu.
As yet it appears as though the Brazilian will be remaining at the Parc des Princes, with manager Thomas Thuchel not wanting to lose any of his players at this stage of the transfer window.