Neymar has failed to report to Paris Saint-Germain training amid reports he is unhappy at the French club.
The Brazilian forward is believed to want a return to Barcelona.
PSG wrote in a statement: "This Monday, July 8, Neymar da Silva Santos Junior was summoned for the resumption of activities of the professional group of Paris Saint-Germain.
"Paris Saint-Germain found that the player Neymar Jr did not show up at the agreed time and place, without having been authorized by the club in advance.
"Paris Saint-Germain deplores this situation and will take the appropriate measures resulting from it."
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Neymar's father has since defended his son, saying that PSG knew that he would return on July 15.
He told Fox Sports Brazil, per Get French Football News: "PSG knew that he would not return to Paris until July 15th."
It'll be interesting to see how this develops.
Neymar's time in France has been a nightmare.
The Brazilian forward signed for €222 million in 2017, a world record fee, but he has been blighted with injuries ever since.
In his two seasons with the French club he has made 58 appearances and hit the back of the net 51 times.
As well as the injury problems, Neymar has also found himself in trouble this season for his actions off the pitch.
Neymar took to Instagram in March to rant about the officials after his side's controversial Champions League defeat to Manchester United.
The 27-year-old questioned the decision to give United a last minute penalty and told the officials to 'go **** yourselves!'
Neymar then punched a fan after PSG's Coupe de France Final loss against Rennes.
The Brazilian is now said to regret moving from Barcelona to PSG.
Former Barca teammate Adriano confirmed that back in April when he told Cadena SER, per Sport: "I spoke with Neymar about three weeks ago, all of us who have been in Barcelona and left repented and he believes that even more."
His recent actions will only fuel more speculation that he is indeed trying his best to force a move back to his former club.
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