The Brazil star has been heavily linked with a return to Barcelona this summer and his absence will only add fuel to those rumours.
PSG are fuming with the forward, who they paid a world record fee to sign in 2017, and have promised to take action.
An official club statement read: “On Monday 8 July Neymar da Silva Santos Junior was due to return to pre-season activities with the Paris Saint-Germain senior squad.
“Paris Saint-Germain notes that Neymar Jr was not in attendance at the agreed time and place. This was without the club’s prior authorisation.
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